A car traveling at 11.6 meters per second crashes into a barrier and stops in 0.287 meters. What force must be exerted on a child of mass 21.2 kilograms to stop him or her in the same time as the car? Include units in your answer. Answer must be in 3 significant digits. Hint: This is an impulse-momentum theorem problem.

Answers

Answer 1
[tex]\begin{gathered} \text{For car} \\ v_1=11.6\text{ m/s} \\ \Delta x=0.287m \\ v_2=\text{ 0 m/s} \\ t=\text{?} \\ To\text{ find t} \\ v^2_2=v^2_1+2a\Delta x \\ \text{Solving a} \\ v^2_2-v^2_1=2a\Delta x \\ a=\frac{v^2_2-v^2_1}{2\Delta x} \\ a=\frac{(0m/s)^2-(11.6m/s)^2}{2(0.287m)} \\ a=\frac{0m^2/s^2-134.56m^2/s^2}{0.574m} \\ a=\frac{-134.56m^2/s^2}{0.574m} \\ a=-234.42m/s^2 \\ \text{Then} \\ t=\frac{v_2-v_1}{a} \\ t=\frac{0\text{ m/s-11.6m/s}}{-234.42m/s^2} \\ t=\frac{\text{-11.6m/s}}{-234.42m/s^2} \\ t=0.0495\text{ s} \\ \text{For child} \\ m=21.2\text{ kg} \\ v_1=11.6\text{ m/s} \\ v_2=\text{ 0 m/s} \\ t=0.0495\text{ s} \\ F=\text{?} \\ F=\frac{P_2-P_1}{t} \\ P_2-P_1=mv_2-mv_1=m(v_2-v_1),\text{ then} \\ F=\frac{m(v_2-v_1)}{t} \\ F=\frac{(21.2kg)(0\text{ m/s-11.6m/s})}{0.0495\text{ s}} \\ F=\frac{(21.2kg)(-11.6\text{ m/s})}{0.0495\text{ s}} \\ F=\frac{-245.92\operatorname{kg}\text{ m/s}}{0.0495\text{ s}} \\ F=-4968\text{ N} \\ \text{The force to stop the child is 4968 N. The negative means } \\ \text{the force is opposite to the movement} \end{gathered}[/tex]


Related Questions

True or false. Iron fillings can indicate the presence of a magnetic field

Answers

Iron Filings are small shavings of ferromagnetic material.

Ferromagnetic material aligns with a magnetic field.

So, Iron fillings can indicate the presence of a magnetic field

True

A flashlight bulb uses 190.1W of power when the current in the bulb is 0.64 A. What is the voltage?

Answers

Given:

[tex]\begin{gathered} P=190.1\text{ W} \\ I=0.64\text{ A} \end{gathered}[/tex]

The power is given as,

[tex]P=VI[/tex]

Here, P is the power, V is voltage and I is the current.

Rearranging equation in order to get voltage,

[tex]V=\frac{P}{I}[/tex]

Putting all known values,

[tex]\begin{gathered} V=\frac{190.1\text{ W}}{0.64\text{ A}} \\ =297.03\text{ V} \end{gathered}[/tex]

Therefore, the voltage is 297.03 V.

24.A projectile is launched upward at an angle of 30° from thehorizontal with an initial velocity of 145 meters per second. Howfar does the projectile travel horizontally?(a) 1.86 x 10^3 m(b) 2.28 x 10^3 m(c) 4.55 x 10^3 m(d) 9.10 x 10^3 m

Answers

ANSWER:

(a) 1.86 x 10^3 m

STEP-BY-STEP EXPLANATION:

The movement that the projectile takes is a parabolic movement, therefore, the horizontal range is determined as follows:

[tex]x=\frac{v^2_0\cdot\sin (2\theta)}{g}[/tex]

We know the initial velocity, the angle and the gravity, therefore, we replace and calculate the value of the horizontal distance:

[tex]\begin{gathered} x=\frac{145^2\cdot\sin (2\cdot30)}{9.8} \\ x=1857.97\cong1.86\cdot10^3 \end{gathered}[/tex]

The horizontal distance is equal to approximately 1860 meters

The vertices of two rectangles are A(−5,−1),B(−1,−1),C(−1,−4),D(−5,−4) and W(1,6),X(7,6),Y(7,−2),Z(1,−2). Compare the perimeters and the areas of the rectangles. Are the rectangles similar? Explain.Perimeter of ABCD: , Area of ABCD: Perimeter of WXYZ: , Area of WXYZ:

Answers

In order to compare the perimeters and areas, let's first find two adjacent sides of each rectangle.

From ABCD, let's calculate AB and BC:

A and B have the same y-coordinate, so the length is the difference in x-coordinate:

AB = -1 - (-5) = -1 + 5 = 4

B and C have the same x-coordinate, so the length is the difference in y-coordinate:

AB = -1 - (-4) = -1 + 4 = 3

Therefore the perimeter and area are:

[tex]\begin{gathered} P=4+3+4+3=14 \\ A=4\cdot3=12 \end{gathered}[/tex]

Now, for rectangle WXYZ, let's use WX and XY:

W and X have the same y-coordinate, so the length is the difference in x-coordinate:

WX = 7 - 1 = 6

X and Y have the same x-coordinate, so the length is the difference in y-coordinate:

XY = 6 - (-2) = 6 + 2 = 8

So the perimeter and area are:

[tex]\begin{gathered} P=6+8+6+8=28 \\ A=6\cdot8=48 \end{gathered}[/tex]

In order to check if the rectangles are similar, let's check the following relation:

[tex](\frac{P_1}{P_2})^2=\frac{A_1}{A_2}[/tex]

So we have:

[tex]\begin{gathered} (\frac{14}{28})^2=\frac{12}{48} \\ (\frac{1}{2})^2=\frac{1}{4} \\ \frac{1}{4}=\frac{1}{4}\text{ (true)} \end{gathered}[/tex]

Since the relation is true, so the rectangles are similar.

Study the following statements regarding energy and the Law of Energy Conservation: 1. The Law of Energy Conservation means it is saved for another time often for environmental reasons. 2. The Law of Energy Conservation means that there is the same amount of energy before the transfer took place as after 3. When energy is dissipated it means that it disappears. 4. When energy is dissipated it means some of the energy is converted into less useful forms. Which two of the above statements are true?

Answers

Answer:

2. The Law of Energy Conservation means that there is the same amount of energy before the transfer took place as after

4. When energy is dissipated it means some of the energy is converted into less useful forms.

Explanation:

Conservation means that energy is conserved through the transfer. It is equal at the start and at the end.

Energy cannot be created or destroyed, so it doesn't disappear, it changes (converted)

It takes 10 J of energy to move a 2 C charge from point A to point B. What is the potential difference between points A and B?Group of answer choices20 V0.2 V5 VNone of the above

Answers

Take into account that potential difference is defined as the quotient between the energy requierd to move a charge a from a point A to a point B. Use the following formula:

[tex]\Delta V=\frac{\Delta U}{q}[/tex]

where ΔV is the potential difference, ΔU is the energy and q is the charge.

In this case, ΔU = 10J and q = 2C. By replacing these values into the previous formula and by simplifying you obtain:

[tex]\Delta V=\frac{10J}{2C}=5V[/tex]

where 1J/C = 1V (for the units of potential difference)

Hence, the potential difference is 5V

What is the pH of a pure WATER solution if the concentration of H+ in water is 10-7 ?

Answers

Given data:

Comcentration of H+ ion in water,

[tex]\lbrack H^+\rbrack=10^{-7}\text{ }\frac{mol}{l}[/tex]

The pH value is given as,

[tex]pH=-\log _{10}\lbrack H^+\rbrack_{}[/tex]

Substituting all known values,

[tex]pH=-\log _{10}\lbrack10^{-7}\rbrack[/tex]

Since,

[tex]\log _{10}(a^b)=b\times\log _{10}(a)[/tex]

Therefore,

[tex]\begin{gathered} pH=-7\times(-\log _{10}\lbrack10\rbrack) \\ =7\log _{10}\lbrack10\rbrack \end{gathered}[/tex]

Since,

[tex]\log _{10}\lbrack10\rbrack=1[/tex]

Therefore,

[tex]\begin{gathered} pH=7\times1 \\ =7 \end{gathered}[/tex]

Therefore, pH of a pure water solution is 7.

Two objects a distance apart are experiencing 40 N of force. How much force wouldthere be if you DOUBLED the distance between them?

Answers

We know that the masses experience a 40 N force between them, which is a gravitational force due to their mass. So, if we double their distance between them, the force will decrease due to Newton's Gravitational Law.

[tex]F=G\cdot\frac{m_1\cdot m_2}{d^2_{12}}[/tex]

Let's use 2d.

[tex]F=G\cdot\frac{m_1\cdot m_2}{(2d)^2}=G\cdot\frac{m_1\cdot m_2}{4d^2}[/tex]

As you can notice, the force would be divide by 4, so let's do that.

[tex]F=\frac{40N}{4}=10N[/tex]Therefore, if we double their distance, their force would be 10 N.

A park ranger driving on a back country road suddenly sees a deer in his headlights 20m ahead. The ranger, who is driving at 11.4 m/s, immediately applies the brakes andslows down with an acceleration of 3.80 m/s2. How much distance is required for theranger's vehicle to come to rest? Only enter the number, not the units,

Answers

Given data

*The speed of the ranger who is driving at 11.4 m/s

*The given acceleration is a = -3.80 m/s^2

The formula for the distance covered by the ranger's vehicle is given by the kinematic equation of motion as

[tex]\Delta x=\frac{v^2-v^2_0}{2a}[/tex]

*Here v = 0 m/s is the initial speed of the ranger's vehicle

Substitute the values in the above expression as

[tex]\begin{gathered} \Delta x=\frac{0^2-(11.4)^2}{2\times(3.80)} \\ =17.1\text{ m} \end{gathered}[/tex]

The distance is required for the ranger's vehicle to come to rest is calculated as

[tex]\begin{gathered} D=20-17.1 \\ =2.9\text{ m} \end{gathered}[/tex]

The stopping time is calculated as

[tex]v=v_0+at[/tex]

Substitute the values in the above expression as

[tex]\begin{gathered} 0=11.4+(-3.80)(t) \\ t=3.00\text{ s} \end{gathered}[/tex]

A pendulum has a mass of 3kg and is lifted to a height of .3m. What is the maximum speed of the pendulum

Answers

Given data

*The given mass of the pendulum is m = 3 kg

*The given height is h = 0.3 m

The formula for the maximum speed of the pendulum is given as

[tex]v_{\max }=\sqrt[]{2gh}[/tex]

*Here g is the acceleration due to the gravity

Substitute the values in the above expression as

[tex]\begin{gathered} v_{\max }=\sqrt[]{2\times9.8\times0.3} \\ =2.42\text{ m/s} \end{gathered}[/tex]

Hence, the maximum speed of the pendulum is 2.42 m/s

how does gravity affect the range of a projectile?

Answers

Gravity has an effect on a projectile because it reduces the height that it can achieve.

The object's upward movement is stopped by gravity, which pulls it back to earth, limiting the projectile's vertical component. As a projectile moves through the air it is slowed down by air resistance.

Two charges are separated by 6.74 cm. Object A has a charge of 5.0 μ C , while object B has a charge of 7.0 μ C . What is the force on Object A?

Answers

ANSWER

69.34 N

EXPLANATION

Given:

• The charge of object A, qA = 5 x 10⁻⁶ C

,

• The charge of object B, qB = 7 x 10⁻⁶ C

,

• The distance between the objects, r = 6.74 cm = 0.0674 m

Find:

• The force on Object A, FA

The magnitude of the force between two charged particles, q₁ and q₂, separated by a distance r is given by Coulomb's Law,

[tex]F=k\frac{q_1q_2}{r^2}[/tex]

Where k is Coulomb's constant and has a value of approximately 9x10⁹ Nm²/C²,

[tex]F=9\times10^9\frac{Nm^2}{C^2}\cdot\frac{5\times10^{-6}C\cdot7\times10^{-6}C}{0.0674^2m^2}\approx69.34N[/tex]

Hence, the force on object A is 69.34 N.

Calculate the power of a 2057 Ω night light plugged into a 120 V source.

Answers

Lets write the data down:

R = 2057 Ω

V = 120 V

The power of the night light is given by:

[tex]P=\frac{V^2}{R}[/tex]

Plug in the data in the formula:

[tex]\begin{gathered} P=\frac{120^2}{2057} \\ P=\frac{14,400}{2057} \\ P\approx7.0W \end{gathered}[/tex]

The power of the night light is 7.0 W.

Find the direction and magnitude of the vectors (a) A = (25m)x + (-12m)y(b) B = (2.0m)x + (15m)y and(c) A + B

Answers

ANSWER

[tex]\begin{gathered} a)\theta=-25.6\degree;|A|=27.73m \\ b)\theta=82.4\degree;|B|=15.13m \\ c)\theta=6.3\degree^{};|A+B|=27.17m \end{gathered}[/tex]

EXPLANATION

To find the direction of a two-dimensional vector, we apply the formula:

[tex]\theta=\tan ^{-1}(\frac{a_y}{a_x})[/tex]

To find the magnitude of a two-dimensional vector, we apply the formula:

[tex]|a|=\sqrt[]{(a^{}_y)^2+(a_x)^2}[/tex]

a) The direction of vector A is:

[tex]\begin{gathered} \theta=\tan ^{-1}(\frac{-12m}{25m}) \\ \theta=\tan ^{-1}(-0.48) \\ \theta=-25.6\degree \end{gathered}[/tex]

The magnitude of vector A is:

[tex]\begin{gathered} |A|=\sqrt[]{(25m)^2+(-12m)^2} \\ |A|=\sqrt[]{625m^2+144m^2}=\sqrt[]{769m^2} \\ |A|=27.73m \end{gathered}[/tex]

b) The direction of vector B is:

[tex]\begin{gathered} \theta=\tan ^{-1}(\frac{15m}{2m}) \\ \theta=\tan ^{-1}(7.5) \\ \theta=82.4\degree \end{gathered}[/tex]

The magnitude of vector B is:

[tex]\begin{gathered} |B|=\sqrt[]{(2.0m)^2+(15m)^2} \\ |B|=\sqrt[]{4m^2+225m^2}=\sqrt[]{229m^2} \\ |B|=15.13m \end{gathered}[/tex]

c) First, we have to find the sum of A and B:

[tex]\begin{gathered} A+B=(25m)x+(-12m)y+(2.0m)x+(15m)y \\ A+B=(25m+2.0m)x+(-12m+15m)y \\ A+B=(27m)x+(3m)y \end{gathered}[/tex]

The direction of the vector (A + B) is:

[tex]\begin{gathered} \theta=\tan ^{-1}(\frac{3m}{27m}) \\ \theta=\tan ^{-1}(0.1111) \\ \theta=6.3\degree^{} \end{gathered}[/tex]

The magnitude of the vector (A + B) is:

[tex]\begin{gathered} |A+B|=\sqrt[]{(27m)^2+(3m)^2} \\ |A+B|=\sqrt[]{729m^2+9m^2}=\sqrt[]{738m^2} \\ |A+B|=27.17m \end{gathered}[/tex]

A falcon with a mass [tex]m_{1}= 1.21kg[/tex] is diving at a speed of [tex]v_{1}=25.8m/s[/tex] at an angle of[tex]tetha=39.7*[/tex] below horizontal. A pigeon whose mass is [tex]m_{2}=0.62kg[/tex] is flying the the positive x direction at a speed of [tex]v_{2}=8.6m/s[/tex]. The falcon catches the pigeon, and they move as one. Neglect gravity and air resistance.
(a) write an expression for the x component of the final velocity
(b) write an expression for the y component of the final velocity
(c) what is the magnitude, in meters per seconds, of the final velocity?
(e) what is the angel, in degrees below the horizontal, that the final velocity makes with the x axis?

Answers

a ) The expression for the x component of the final velocity = 16 m / s

b ) The expression for the y component of the final velocity = 10.92 m / s

c ) The magnitude of final velocity = 19.37 m / s

m1 = 1.21 kg

m2 = 0.62 kg

Along x-axis,

u1 = u cos θ

u1 = 25.8 cos 39.7°

u1 = 19.87 m / s

u2 = 8.6 m / s

According to law of conservation of momentum

m1u1 + m2u2 = ( m1 + m2 ) vx

( 1.21 * 19.87 ) + ( 0.62 * 8.6 ) = ( 1.21 + 0.62 ) vx

vx = ( 24 + 5.3 ) / 1.83

vx = 16 m / s

Along y-axis,

u1 = u sin θ

u1 = 25.8 sin 39.7°

u1 = 16.5 m / s

u2 = 0

m1u1 = ( m1 + m2 ) vy

( 1.21 * 16.5 ) = ( 1.21 + 0.62 ) vy

vy = 19.98 / 1.83

vy = 10.92 m / s

v = √ vx² + vy²

v = √ 16² + 10.92²

v = √ 256 + 119.25

v = √ 375.25

v = 19.37 m / s

tan θ = vy / vx

tan θ = 10.92 / 16

tan θ = 0.68

θ = 34.22°

Therefore,

a ) The expression for the x component of the final velocity = 16 m / s

b ) The expression for the y component of the final velocity = 10.92 m / s

c ) The magnitude of final velocity = 19.37 m / s

d ) The angle below the horizontal, that the final velocity makes with the x axis = 34.22°

To know more about law of conservation of momentum

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A 1000-watt kettle is connected to a 220-volt power source. Calculate the resistance of the kettle

Answers

The power of kettle is given as,

[tex]P=\frac{V^2}{R}[/tex]

Plug in the known values,

[tex]\begin{gathered} 1000\text{ W=}\frac{(220V)^2}{R} \\ R=\frac{(220V)^2}{1000\text{ W}}(\frac{1\text{ ohm}}{1V^2W^{-1}})_{} \\ =48.4\text{ ohm} \end{gathered}[/tex]

Thus, the resistance of the kettle is 48.4 ohm.

I take my calculator from the top of a building and toss it straight upward at 9 m/s from a 23 m tall building.A. what is the speed of the Calculator right before it hits the ground? B. What is the acceleration of the calculator at peak height? C. How much time does it take for the calculator to reach peak height?

Answers

Given,

The initial velocity with which the calculator was thrown, u=9 m/s

The height of the building, h=23 m

A.

When the calculator reaches the peak height, its velocity will become zero. That is v=0 m/s

And while it is going up the acceleration due to gravity will be acting downward. Thus the acceleration due to gravity will be a negative value.

From the equation of motion,

[tex]v^2-u^2=2gs_{}[/tex]

Where s is the peak height reached by the calculator and g is the acceleration due to gravity.

On substituting the known values,

[tex]\begin{gathered} 0-9^2=2\times-9.8\times s \\ \Rightarrow s=\frac{-9^2}{2\times-9.8} \\ =4.13\text{ m} \end{gathered}[/tex]

Thus the total height reached by the calculator from the ground is

[tex]\begin{gathered} H=h+s \\ =23+4.13 \\ =27.13 \end{gathered}[/tex]

After reaching the peak height, the calculator starts descending. This descent starts with the initial velocity of v=0 m/s. And the acceleration due to gravity will be in the direction of motion of the calculator. Thus it will be a positive value.

From the equation of motion,

[tex]v^2_0-v^2=2gH[/tex]

where v₀ is the velocity of the calculator right before it hits the ground.

On substituting the known values,

[tex]\begin{gathered} v^2_0-0=2\times9.8\times27.13 \\ \Rightarrow v_0=\sqrt[]{2\times9.8\times27.13}^{} \\ =23.06\text{ m/s} \end{gathered}[/tex]

Thus the speed of the calculator right before it hits the ground is 23.06 m/s

B.

The acceleration of the calculator is a constant value. It is always equal to the acceleration due to gravity.

Thus the acceleration of the calculator at peak height is 9.8 m/s²

C.

From the equation of motion,

[tex]v=u+gt[/tex]

Where t is the time it takes for the calculator to reach the peak height.

On substituting the known values,

[tex]\begin{gathered} 0=9+(-9.8)t \\ \Rightarrow t=\frac{-9}{-9.8} \\ =0.92\text{ s} \end{gathered}[/tex]

Thus it takes 0.92 s for the calculator to reach the peak height.

A 200-turn solenoid is 20.0 cm long and carries a current of 3.25 A.1. Find the magnetic field inside the solenoid in [mT].2. Find the force in [µN] exerted on a 15.0x10-6 C charged particle moving at 1050 m/s through the interior of the solenoid, at an angle of 11.5° relative to the solenoid’s axis.

Answers

Given,

Number of turns, N=200

Length of teh solenoid, l=20 cm=0.2 m

Current, I=3.25 A.

Charge is

[tex]q=15\times10^{-6}C[/tex]

The velocity is v=1050 m/s

Angle is

[tex]\theta=11.5^o[/tex]

To find

a. Magnetic field inside the solenoid

b. The force

Explanation

a. The magnetic field is

[tex]B=\mu_onI[/tex]

n is the number of turns per unit length.

Thus,

[tex]\begin{gathered} n=\frac{N}{l} \\ \Rightarrow n=\frac{200}{0.2}=1000 \end{gathered}[/tex]

So,

[tex]B=4\pi\times10^{-7}\times1000\times3.25=4.08\times10^{-3}=4.08\text{ mT}[/tex]

b. The magnetic force is given by:

[tex]\begin{gathered} F=\text{qvBsin}\theta \\ \Rightarrow F=15\times10^{-6}\times1050\times4.08\times10^{-3}\sin 11.5=1.28\times10^{-5}N \end{gathered}[/tex]

Conclusion

a.The magnetic field is 4.08 mT

b.The magnetic force is

[tex]1.28\times10^{-5}N[/tex]

Use g = 10 m/s/s for this problem. A force is applied to a block through tension in a rope, at an angle to the horizontal as shown. The block is being pulled across a rough surface. The mass of the block is 71 kg. The tension in the rope is 1197 N. The angle from horizontal is 15 degrees. The coefficient of friction μ is 0.3.

Answers

Answer:

14.6 m/s²

Explanation:

First, we will make the free body diagram

Since the net vertical force is equal to 0 because the block is not moving up, we can write the following equation

[tex]\begin{gathered} F_{nety}=F_n+F_{Ty}-mg=0 \\ F_n+F_T\sin15-mg=0 \end{gathered}[/tex]

Then, we can solve for the normal force and replace Ft = 1197 N, m = 71 kg and g = 10 m/s²

[tex]\begin{gathered} F_n=mg-F_T\sin15 \\ F_n=(71\text{ kg\rparen\lparen10 m/s}^2)-(1197N)(0.26) \\ F_n=400.2\text{ N} \end{gathered}[/tex]

Now, we can write the following equation for the net horizontal force

[tex]\begin{gathered} F_{net}=F_{Tx}-F_f=ma \\ F_T\cos15-\mu F_n=ma \end{gathered}[/tex]

Where μ is the coefficient of friction and a is the acceleration of the block. Solving for a and replacing Ft = 1197 N, m = 71 kg, Fn = 400.2 N and μ = 0.3, we get

[tex]\begin{gathered} a=\frac{F_T\cos15-\mu F_n}{m} \\ \\ a=\frac{(1197\text{ N\rparen}\cos15-0.3(400.2N)}{71\text{ kg}} \\ \\ a=14.6\text{ m/s}^2 \end{gathered}[/tex]

Therefore, the acceleration of the block is 14.6 m/s²

Which choice is a valid way to construct a motion diagram?1) Add together the average speeds of the various objects in motion.2) Take a series of photographs at equal time intervals of a moving object, perpendicular to the direction of motion; overlay the images to see how the position changes with time.3) Draw vectors to represent the speeds involved.4) Add vectors in a head-to-tail manner to determine the resultant vector.

Answers

A motion diagram displays the location of an object at various equally spaced time intervals in the same diagram. This allows us to visualize the motion of the object.

From the described procedures, the one which would be useful to make a motion diagram, is:

Option 2) Take a series of photographs at equal time intervals of a moving object, perpendicular to the direction of motion; overlay the images to see how the position changes with time.

An object with a mass of 5kg is moving with a force of 25N. What is the object's acceleration?

Answers

According to Newton's second law, F=ma

Where F is the force acting on the object, m is the mass of the object, and a is the acceleration of the body due to the applied force.

It is given in the question,

m=5 kg

F=25 N

On substituting the known values in the above equation,

[tex]25=5\times a[/tex]

On rearranging the above equation,

[tex]a=\frac{25}{5}=5m/s^2[/tex]

Therefore the object's acceleration is 5 m/s²

A force acting on an object does no work if1. a machine is used to move the object.2. the force is greater than the force of friction.3. the force acts perpendicular to the direction of the object’s motion.4. the object accelerates.

Answers

The work done of any object is defined by

[tex]W=Fd\cos \theta[/tex]

Here, F is the force acting on the object.

d is the displacement of the object due to the force applied.

[tex]\theta[/tex]

is the angle between force and displacement.

For work done to become zero, the applied force can be zero, or displacement can be zero, or cosine angle is zero.

Cosine angle can be zero if force and displacement are perpendicular to each other.

Thus, if the force acts perpendicular to the direction of the object's motion, no work is done..

What is the power rating of a heating coil with a resis-tance of 12 12 that draws a current of 20 A?

Answers

According to the problem, we have the following

[tex]\begin{gathered} R=12 \\ I=20 \end{gathered}[/tex]

We have to use Ohm's law

[tex]V=I\cdot R[/tex]

Let's replace the given information

[tex]V=20\cdot12=240[/tex]Hence, the power is 20 Volts.

A car stereo pulls 2.89 A from a car's battery. If the battery has a voltage of 12 V, how much power does it use?

Answers

In order to calculate the power, we can multiply the voltage and the current:

[tex]P=I\cdot U[/tex]

So we have:

[tex]\begin{gathered} P=2.89\cdot12\\ \\ P=34.68\text{ W} \end{gathered}[/tex]

Therefore the power is 34.68 W.

SORRY IF ITS IN THE WRONG SUBJECT. I NEED SOMEONE ANSWER ASAP. text to answer the question. Most games that are played with a standard deck of playing cards are called trick games. In such a game, each player will take a turn playing a card, and whoever plays the winning card takes them all. These cards make up a trick, which the winner puts face-side down in a stack before playing the first card for the next round. Would the information in the text be an effective source to help answer the research question "What are the most popular magic tricks? (1 point) O No, because magic tricks that use playing cards are unpopular. O No, because the source is about card games instead of magic tricks. OYes, because the source is written by an expert on the subject. OYes, because the source explains a type of trick. ​

Answers

Answer: the answer should be "No, because the source is about card games instead of magic tricks."

Explanation: sorry for answering 2 weeks later

Answer:

B

Explanation:

Your friend is flying a hot air balloon and you are recording them from below. When you start filming, the hot air balloon is at an angle of 63 degrees above you while staying 100 feet away from where it launched. After 5 seconds, the angle has increased to 67.9 degrees. How fast is your friend rising in feet per seconds and miles per hour.

Answers

Answer:

10 ft/s and 6.818 mi/hr

Explanation:

We can represent the situation with the following diagram:

When the angle is 63 degrees, the value of h can be calculated using a trigonometric function as:

[tex]\tan 63=\frac{h_i}{100}[/tex]

Because h is the opposite side and 100 ft is the adjacent side. Solving for h, we get:

[tex]\begin{gathered} h_i=100\times\tan 63 \\ h_i=196.26\text{ ft} \end{gathered}[/tex]

In the same way, when the angle is 67.9 degrees, we can calculate the height as follows:

[tex]\begin{gathered} \tan 67.9=\frac{h_f}{100} \\ h_f=100\times\tan 67.9 \\ h_f=246.27ft \end{gathered}[/tex]

Now, we can calculate the speed in ft per second as follows:

[tex]s=\frac{h_f-h_i}{t}=\frac{246.27ft-196.24ft}{5s}=10\text{ ft/s}[/tex]

Finally, 1 mile = 5280 ft and 1 hour = 3600 seconds, so we can convert to miles per hour as:

[tex]10\text{ ft/s }\times\frac{1\text{ mile}}{5280\text{ ft}}\times\frac{3600}{1\text{ hour}}=6.818\text{ mi/hr}[/tex]

Therefore, the answers are:

10 ft/s and 6.818 mi/hr

4. A 45.8 kg block is placed on an inclined plane that is 44.2 degrees from the horizontal. What isthe acceleration of the block? Ignore friction.Challenge Question: 5. The same block in problem #4 is placed on the same inclined plane from problem #4. However, now there is friction. If the coefficient of kinetic friction is 0.25, what is the Friction force?(I already answered question 4, i just need help with question 5)

Answers

Explanation

Step 1

free body diagram

Step 2

sum of the forces on x-axis

a)x

[tex]\begin{gathered} F=\text{mg}\cos \text{ }\theta=ma \\ \text{replace} \\ F=\text{ 45.8}\cdot9.81\cdot\cos \text{ 44.2=ma} \\ 322.10=45.8a \\ a=\frac{322.10}{45.8} \\ a=703\text{ }\frac{\text{m}}{s^2} \end{gathered}[/tex]

A fire is an example of ________________ reaction, because heat is _____________ the system.

A. exothermic; leaving

B. exothermic; entering

C. endothermic; leaving

D. endothermic; entering

Answers

Because heat is being introduced into the system, a fire is just an example of an exothermic reaction.

The right response is B.

What is exothermic example?

Any process was considered to be exothermic if it produces heat while also undergoing a net decrease in standard enthalpy change. Examples include any type of combustion, iron rusting, and water freezing. Exothermic processes are those that discharge warmth and energy into the surrounding environment.

What process are exothermic?

If heat is released from the system into the environment, the reaction or change is exothermic. The temperature of the environment rises because it is absorbing heat from the system.

To know more about exothermic visit:

brainly.com/question/4345448

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Let f(x) = 5* Let g(x) = 54 - 7 = - g Which statement describes the graph of g(x)with respect to the graph of f(x)? O g(x)is translated 7 units right from f(x). O g(x)is translated 7 units down fromf (x). O g(x)is translated 7 units left fromf (x). O g(x)is translated 7 units up fromf (x).

Answers

Answer:

[tex]\text{Second Option}[/tex]

Explanation: The two functions are:

[tex]\begin{gathered} f(x)=5^x \\ g(x)=5^x-7 \end{gathered}[/tex]

The graphs of these two functions are as follows:

From this we can infer that the answer is:

Hi I do know the answer to this it’s be answered for me twice already just looking for a bit of a deeper explanation physical and why and how?

Answers

4.1

The free body diagram is shown below

Newton's first law of motion states that a body at rest or in motion would continue to be at rest or in motion unles an external force acts on it causing it to start or stop moving.

Sum of forces in the horizontal direction, Fx = - Fr + F

Sum of forces in the vertical direction, Fy = N + FSinθ - mg

Since the motion is along the horizontal axis, There would not be an acceleration in the y axis. Thus, Fy = 0

Force = mgCosθ

4.3) From the information given,

mass, m = 50kg

Force =

Forcce = 50 x 9.81Cos20

4.4)

Fy = 0

N + FSinθ - mg = 0

N = mg - FSinθ

N = 50 * 9.81 - FSin20

N = 490.5 - FSin20

N = 490.5 - 0.342F

4.5)

Frictional force = coefficient of friction x normal force

From the information given,

coefficient of friction = 0.4

Frictional force = 0.4(490.5 - 0.342F)

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