Can work ever be negative?
A)Yes, when force is negative
B)Yes, when displacement is negative
C)Yes, when cos(e) is negative
D)No, work can never be negative

Answer:

the tangential velocity of the student is 4.89 m/s.

Explanation:

Given;

the radius of the circular path, r = 3.5 m

duration of the motion, t = 4.5 s

let the student's tangential velocity = v

The tangential velocity of the student is calculated as follows;

[tex]v = \frac{2\pi r}{t} \\\\v = \frac{2 \pi \times 3.5}{4.5} \\\\v = 4.89 \ m/s[/tex]

Therefore, the tangential velocity of the student is 4.89 m/s.

Answer:

17,190 years old

Explanation:

D

Answer:

attractive/magnetic

mark me brainliestt :))

Answer:

True its got to be true

Explanation:

how else does a hoverboard float lol

Answer:

It's true

Explanation:

So true..

Answer:

Conserve money means to save money. Conserve resources means the same thing but with resources; so conserve resources means to save resources.

Explanation:

Answer:

If research results can be replicated, it means they are more likely to be correct.

Answer: There are many things that have to be checked in order to know

Explanation:

For repeatability to be established, the following conditions must be in place: the same location; the same measurement procedure; the same observer; the same measuring instrument, used under the same conditions; and repetition over a short period of time.

Hope this helps!

Pls Mark me brainliest

Answer:

Nuclear power is presently a sustainable energy source, but could become completely renewable if the source of uranium changed from mined ore to seawater. Since U extracted is continuously replenished through geologic processes, nuclear would become as endless as solar.

Electric currents, changes in electric fields, or charged particles with inherent angular momentum produce the magnetic field.

A magnetic field, a vector field that describes the magnetic field on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field is subject to a force that is perpendicular to the magnetic field and has its own velocity.

The force that draws objects like iron is known as the magnetic force. The attraction or repellence between two magnetic materials is known as magnetic force. Iron is one of the ferromagnetic materials.

Given the facts, the magnetic field is typically present whenever charged particles with intrinsic angular momentum or spin are in the field or space, as well as whenever there are changes in the electric fields or currents.

Now, two of Maxwell's equations explain the magnetic fields produced by electric currents and shifting electric fields.

Magnetic fields are produced whenever a charge moves. When more charge is transferred about, a magnetic field grows stronger.

Hence, when there is an electric field, there is also a magnetic field.

Go here for additional information about magnetic fields.

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True

The rate at which work is done is referred to as power. A task done quite quickly is described as having a relatively large power. The same task that is done more slowly is described as being of less power. Both tasks require he same amount of work but they have a different power.

Answer:

Answer:

Gravitational potential=mgh

=50×10×2.5

=1250J

option a

Answer:

Fossil fuels store energy from the sun as

Explanation:

Answer:

Due to wind and waves of water.

Explanation:

They wonder that the ball will float back to the beach because of the wind and the waves of the water. The wind blows towards the beach which moves the water in the form of waves towards the beach so if the ball lands in the water, it will floats on the surface of water and move towards the beach with the help of wind and waves of the sea. The ball floats on the water due to its lighter weight and lower density as compared to water.

Answer:

120N

Explanation:

Weight=mass x acceleration due to gravity (on the planet)

Mass of an astronaut is 75kg and value of acceleration due to gravity on moon is 1.6m/s2

Weight of astronaut on moon=mass of astronaut x value of acceleration due to gravity on moon

75kg x 1.6m/s2

=120N

Answer:

A) blindness

Explanation:

Answer:

the distance traveled by the car is 42.98 m.

Explanation:

Given;

mass of the car, m = 2500 kg

initial velocity of the car, u = 20 m/s

the braking force applied to the car, f = 5620 N

time of motion of the car, t = 2.5 s

The decelaration of the car is calculated as follows;

-F = ma

a = -F/m

a = -5620 / 2500

a = -2.248 m/s²

The distance traveled by the car is calculated as follows;

s = ut + ¹/₂at²

s = (20 x 2.5) + 0.5(-2.248)(2.5²)

s = 50 - 7.025

s = 42.98 m

Therefore, the distance traveled by the car is 42.98 m.

Answer:

Solid objects will deform when adequate loads are applied to them; if the material is elastic, the object will return to its initial shape and size after removal. This is in contrast to plasticity, in which the object fails to do so and instead remains in its deformed state.

Explanation:

Answer:

It is false

Explanation:

because when it like a rolling ball it can deform no matter what unlesss you throw it at the ground really hard then it breaks but a soft or sometimes metal yeah it can deform but not all things solid deform.

Answer:

[tex]8\:\text{m/s}[/tex]

Explanation:

From Newton's 2nd Law, we have [tex]\Sigma F=ma[/tex]. Using this, we can find the acceleration of the object:

[tex]9.20=2.30a,\\a=\frac{9.20}{2.30}=4\:\mathrm{m/s^2}[/tex].

Now that we've found the block's acceleration, we can use the following kinematics equation to find its final velocity after 2 seconds:

[tex]v_f=v_i+at,\\v_f=0+4(2),\\v_f=\boxed{8\:\text{m/s}}[/tex]

*Assumption: The block is initially at rest and has a initial velocity of zero. Otherwise, the question is unsolvable.

Answer:

19.24 volts

Explanation:

From Ohm's law,

Applying,

V = IR.................. Equation 1

Where V = Voltage applied, I = currentflowing across the resistor, R = Resistance

From the question,

Given: I = 0.225 A, R = 85.5 Ohm

Substitute these values into equation 1

V = (0.225×85.5)

V = 19.24 volts

Hence the Voltage applied is 19.24 Volt

Answer:

19.24

Explanation:

acellus

Answer:

v= 8.3 m/ s^-1

Explanation:

S=vt

v= S/t

v= 250 m/ 30 s

v= 8.3 m/ s^-1

Answer:

1. Heinrich Hertz.

2. James Clerk Maxwell.

3. Thomas Young.

4. Christiaan Huygens.

5. Isaac Newton.

Explanation:

Light wave can be defined as an electromagnetic wave that do not require a medium of propagation for it to travel through a vacuum of space where no particles exist.

However, the various definitions of light according to early scientists include the following;

1. Heinrich Hertz: Light is a wave that has similar properties as radio waves. Heinrich Rudolf Hertz was a German physicist born on the 22nd of February, 1857 in Hamburg, Germany. The unit of frequency ("Hertz") of an electromagnetic wave was named after him.

2. James Clerk Maxwell: Light is a wave made of electric and magnetic fields. James Clerk Maxwell was a Scottish physicist born on the 13th of June, 1831 in Edinburgh, United Kingdom. He was famously known for his work in the formulation of the classical theory of electromagnetic radiation.

3. Thomas Young: Light is a wave because this property can explain interference.

4. Christiaan Huygens: Light is a wave because it bends when it hits barriers and openings.

5. Isaac Newton: Light is made of particles because it travels only in straight paths.

Answer:

See image

Explanation:

Light wave can be defined as an electromagnetic wave that do not require a medium of propagation for it to travel through a vacuum of space where no particles exist.

However, the various definitions of light according to early scientists include the following;

1. Heinrich Hertz: Light is a wave that has similar properties as radio waves. Heinrich Rudolf Hertz was a German physicist born on the 22nd of February, 1857 in Hamburg, Germany. The unit of frequency ("Hertz") of an electromagnetic wave was named after him.

2. James Clerk Maxwell: Light is a wave made of electric and magnetic fields. James Clerk Maxwell was a Scottish physicist born on the 13th of June, 1831 in Edinburgh, United Kingdom. He was famously known for his work in the formulation of the classical theory of electromagnetic radiation.

3. Thomas Young: Light is a wave because this property can explain interference.

4. Christiaan Huygens: Light is a wave because it bends when it hits barriers and openings.

5. Isaac Newton: Light is made of particles because it travels only in straight paths.

Answer:

784,000 J

Explanation:

For this question we can simply use the equation for the Kinetic Energy which is : [tex]\frac{1}{2} mv^2[/tex], where m = the mass and v = the velocity.

So let's put the values given into the equation.

[tex]K.E = \frac{1}{2} *2000*(28)^2 = 784000 J[/tex]

The car's kinetic energy is 784,000 Joules

Answer:

A gas is not used in hydraulic machines as the fluid because gas is easily compressible and so if a gas is used, the energy would mostly go into compressing a gas. Therefore a liquid is used in hydraulic machines as the fluid.

Explanation:

I got you bro:)

Initial velocity of car is 0.

Final velocity of car is 36 km/h.

Time taken to attain final speed is 2 minutes.

What is the acceleration of car ?

v = u + at

First change the final velocity from km/h to m/s and also time to seconds.

[ To change km/h to m/s multiply by 5/18 ]

➙ Final velocity = 36(5/18) = 10 m/s.

[ 1 minutes = 60 seconds ]

➙ 2 minutes = 2(60) = 120 seconds.

Now, we have

v = 10 m/s.

u = 0 m/s.

t = 120 s.

Hence, the acceleration of car is 0.083 m/s².

➟ The rate of change of velocity is called acceleration. It is denoted by a.

➟ The velocity at which motion starts is termed as initial velocity. It is denote by u.

➟ The last velocity of an object after a period of time. It is denoted by v.

[tex]\boxed{\large{\bold{\blue{ANSWER~:) }}}}[/tex]

By 1st Equation of motion

we know that,

[tex]\boxed{\large{\sf{v \: = u \: + a \: t}}}[/tex]

according to the question,

[tex]10 = 0 + a \times 120\\\\a \: = \frac{10}{120}\\\\a \: = \frac{1}{12}\\\\a=0.083\: m {s}^{ - 2}[/tex]

Therefore,

Acceleration of the car is 0.083 ms^-2

Answer:

I believe the answer is C.

Explanation: Hope this helps and have a great day! :)

Answer:

The velocity of one of the trains is 15 m/s

The velocity of the other train 5 m/s

Explanation:

The given parameters of the two trains and the motion of the trains are;

The length of each train, l = 100 m

The time it takes one train to overtake the other, Δt₁ = 20 s

The time it takes the one train to cross the other, Δt₂ = 10 s

Let 'v₁' represent the velocity of one of the trains, and let 'v₂' represent the velocity of the other train, we have;

When one train overtakes the other, the trains are moving in the same direction and the relative velocity of the overtaking train, v = v₁ - v₂

The distance the train travels when overtaking or crossing, d = 2 × l

∴ d = 2 × 100 m = 200 m

d = 200 m

Therefore, we get;

v = v₁ - v₂ = d/Δt₁ = (200 m)/(20 s) = 10 m/s

∴ v₁ - v₂ = 10 m/s                     [tex]{}[/tex]                    Equation (1)

When one train crosses the other train, the trains are moving in opposite directions on the different tracks, therefore, we have;

For the overtaking trains, v = v₁ + v₂ = d/Δt₂ = (200 m)/(10 s) = 20 m/s

∴ v₁ + v₂ = 20 m/s                              [tex]{}[/tex]          Equation (2)

Adding equation (1) to equation (2) gives;

v₁ - v₂ + v₁ + v₂ = 2·v₁ = 10 m/s + 20 m/s = 30 m/s

∴ v₁ = 30 m/s/2 = 15 m/s

The velocity of one of the trains, v₁ = 15 m/s

From equation (2), we  have;

v₁ + v₂ = 20 m/s

v₂ = 20 m/s - v₁

∴ v₂ = 20m/s - 15 m/s = 5 m/s

The velocity of the other train, v₂ = 5 m/s.

Answer:

The wavelength of the wave in shallow water is 2.91 m.

Explanation:

Given;

frequency of the wave, f = 1.1 Hz

speed of the wave in deep water, v₁ = 5.7 m/s

speed of the wave in shallow water, v₂ = 3.2 m/s

The wavelength of the wave in the deep water is calculated as;

λ₁ = v₁/f

λ₁ = 5.7 / 1.1

λ₁ = 5.18 m

The wavelength of the wave in the shallow water is calculated as;

λ₂ = v₂/f

λ₂ = 3.2 / 1.1

λ₂ = 2.91 m

Therefore, the wavelength of the wave in shallow water is 2.91 m.