4. A weightlifter raises a mass mat a constant speed to a height h in time t. Which of the following
expressions corresponds with the work done by the weightlifter?
a. mgh
b.-mgh
C. mgh/t
d. -mgh/

Answers

Answer 1

Answer:

a. mgh

Explanation

The work done by the lifter is equal to its potential energy since he is covering a height and under the influence of gravity.

potential energy = mass * acceleration due to gravity * height

m is the mass

g is the acceleration due to gravity

h is the height

Hence the required workdone = PE = mgh


Related Questions

A beaker containing ice and water is placed on a warm hotplate. What type of change would you expect
the ice to undergo​

Answers

Answer:

Solid to liquid

Explanation:

Ice cubes are solid, adding heat to the beaker will melt the ice cubes to water.

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Answer using mass m= F divided by a

Also use kilograms {kg}


A tiny aeroplane accelerates at 35 m/ s2 with a force of 20 N. What is the mass of the aeroplane?

Answers

Answer:

0.57 kg

Explanation:

We are given that

Force, F=20 N

Acceleration ,a =[tex]35m/s^2[/tex]

We have to find the mass of Aero-plane.

To find the value of mass we will divide the force by acceleration.

We know that

Force, F=ma

Using the formula

[tex]20=m\times 35[/tex]

[tex]\frac{20}{35}=m[/tex]

[tex]m=0.57 kg[/tex]

Hence, the mass of the aero-plane=0.57 kg

Select all that apply. According to scientists, the distribution of volcanoes throughout the world…

Forms a specific pattern across fault lines
Corresponds to plate boundaries
Is constantly changing and shifting
Is fairly even and widespread

Answers

Corresponds to plate boundaries
Is constantly changing and shifting

Answer:

Corresponds to plate boundaries

Is constantly changing and shifting

Explanation:

Unbeknownst to the students, every time the school floors are waxed, Mr. Tracy, the principal, likes to slide down the Hallway in his socks. Mr. Tracy weighs 85 kg and the coefficient of sliding friction between his socks and the floor is 0.120. What is the force of friction that opposes Mr. Tracy's motion down the hall?

Answers

Answer:

f = 99.96 N

Explanation:

Weight of Mr. Tracy, W = 85 kg

The coefficient of sliding friction between his socks and the floor is 0.12.

We need to find the force of friction that opposes Mr. Tracy's motion down the hall.

The force of friction is given by :

[tex]f=\mu mg\\\\f=0.12\times 85\times 9.8\\\\f=99.96\ N[/tex]

So, the required force of friction is 99.96 N.

Planets A and B have the same mass, but planet A is half the size of planet B. Which statement correctly explains the weight you would experience on each planet? O A. You would weigh more on planet A because the distance between you and the planet's center of gravity would be smaller. B. You would weigh the same on both planets because the masses of the planets are the same. 2 C. You would weigh the same on both planets because your mass would be the same on both. D. You would weigh less on planet A because the distance between you and the planet's center of gravity would be smaller.​

Answers

Answer:

I would say A

Explanation:

the closer you are to a planets center of gravity i feel you would weigh more.

Skater begins to spend with arms held out at shoulder height. The skater wants to match the speed of the spin to the beat of the music. How does the skater use knowledge of the conservation of momentum to do this?

Answers

Answer:

the moment of inertia with the arms extended is Io and when the arms are lowered the moment

I₀/I > 1    ⇒   w > w₀

Explanation:

The angular momentum is conserved if the external torques in the system are zero, this is achieved because the friction with the ice is very small,

           L₀ = L_f

           I₀ w₀ = I w

          w =[tex]\frac{I_o}{I}[/tex] w₀

where we see that the angular velocity changes according to the relation of the angular moments, if we approximate the body as a cylinder with two point charges, weight of the arms

          I₀ = I_cylinder + 2 m r²

where r is the distance from the center of mass of the arms to the axis of rotation, the moment of inertia of the cylinder does not change, therefore changing the distance of the arms changes the moment of inertia.

If we say that the moment of inertia with the arms extended is Io and when the arms are lowered the moment will be

        I <I₀

        I₀/I > 1    ⇒   w > w₀

therefore the angular velocity (rotations) must increase

in this way the skater can adjust his spin speed to the musician.

The initial velocity is referring how fast the object is moving at the end of the scenario or problem.
True
False

Answers

Answer:

Fasle. , is correct answer hope it helps

There are two main types of exercise: (1) exercise, which uses oxygen for energy, and (2) exercise, which does not.

a)
1= anaerobic, 2= aerobic

b)
1= aerobic, 2= anaerobic

Answers

Answer:

b

Explanation:

Answer:

B

Explanation:

state whether a speedometer reading of 45 km/h is the average or instantaneous speed of the car

Answers

thats is instantaneous bc it’s in the moment

How would you describe impulse in the simplest way possible

Answers

Answer:

Explanation:

 impulse is a sudden force or desire — this could be an electrical impulse, or an impulse to get some pizza.

If you act on a sudden feeling or thought, you’re following an impulse.

That's like a whim: an impulse isn't something you've given a lot of thought. Another meaning of impulse is an electrical charge or pulse. Electrical impulses are coursing through wires all through your house every day. Both kinds of impulses make things happen. The electrical impulse keeps the refrigerator going, and then you have an impulse to eat all the ice cream in the fridge.

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In any collision (crash) the_
is ALWAYS constant​

Answers

Answer:

In any collision (crash) the momentum

is ALWAYS constant

In any collision (crash) the momentum is always constant​, whether it is an elastic collision or an inelastic collision the momentum before and after the collision is conserved

What is elastic collision?

It is the type of collision in which the total momentum, as well as the kinetic energy of the system, is conserved.

The momentum is always preserved before and after any collision (crash), regardless of whether it is an elastic collision or an inelastic collision.

In the inelastic collision, the momentum is conserved but the kinetic energy of the quantity is not conserved.

The momentum of a quantity is preserved regardless of the type of collision, whether it be an elastic collision or an inelastic collision; the momentum of the quantity will always be conserved.

Hence, The momentum is always preserved before and after any collision (crash), regardless of whether it is an elastic collision or an inelastic collision.

Learn more about the collision from here

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a 28 kg student stand on the surface of the Earth. What is the magnitude of the
gravitational force of the earth on the student?

Answers

Answer:

F = 274.68[N]

Explanation:

The gravitational force is equal to the weight of a body, or this case that of a person. Weight can be calculated by means of the product of mass by gravitational acceleration. In this way we have the following equation:

[tex]F=m*g[/tex]

where:

F = force or weight [N]

m = mass = 28 [kg]

g = gravity acceleration = 9.81 [m/s²]

Now replacing:

[tex]F=28*9.81\\F=274.68[N][/tex]

what is the difference between an open and closed circuit?

Answers

A closed circle means the number is included and an open circle means its not.

6. Abdul moves a magnetic toy train away from a magnet that cannot move. What happens to the

potential energy in the system of magnets during the movement?

a

The potential energy decreases because the train moves in the same direction as the

magnetic force.

b

The potential energy decreases because the train moves against the magnetic force.

С

The potential energy increases because the train moves against the magnetic force.

d

The potential energy does not change because the magnets in the system do not change.

Yeah

Answers

Answer: Potential energy increases because the train moves against the magnetic force.

Explanation:

When the magnetic toy train is moved away from a magnet that cannot move, the potential energy in the system of magnets during the movement is affected as there's an increase in the potential energy because the train moves against the magnetic force.

We should note that the potential energy simply means the energy that is stored in the magnetic toy. Since the magnetic toy has been moved away from the magnet, the likelihood of its attraction will reduce thereby there'll be a rise in the potential energy.

Give me the example of junction law and loop law?

Answers

Answer:

According to the Junction rule, in a circuit, the total of the currents in a junction is equal to the sum of currents outside the junction. Kirchhoff’s Voltage Law goes by several names as Kirchhoff’s Second Law and Kirchhoff’s Loop Rule. According to the loop rule, the sum of the voltages around the closed loop is equal to null.

Explanation:

Suppose a mass of 0.500 kg falls from 3050m. What potential energy is associated with the coin when its speed is 30.0 m/s?

Answers

Answer:

14945 J

Explanation:

Glad you asked this question!

The speed is  irrelevant in this question. It perhaps was put out to throw you off.

P.E = mgh = (0.5 * 9.8 * 3050) = 14945 Joules

I can't wait till Christmas!!!

Answers

Answer:

Good for you!

The height of a transverse waves is known as its?

Answers

Answer:

amplitude

Explanation:

wave is a called the crest, and the low point is called the trough. For longitudinal waves, the compressions and rarefactions are analogous to the crests and troughs of transverse waves. The distance between successive crests or troughs is called the wavelength. The height of a wave is the amplitude.…

Cual es el volumen en m³ y en litros de 3000N de aceite de oliva cuyo peso espesifico es de 9016 N/M³

Answers

Answer: I am sorry but I don't know what you're trying to say.

Explanation: Hope

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What is the force of a 3 kg skateboard accelerating at a rate of 4m/s2?

Plug in the numbers: Force= mass x acceleration

Answers

Answer:

F = 12 N

Explanation:

F = m × a

F = 3 × 4

F = 12 kg m/s²

F = 12 N

Gravitational force acts on all objects in proportion to their masses. Why then, a heavy object does not fall faster than a light object?

Plss help!!!!

Answers

Answer:

This is because the acceleration of objects due to gravity is independent of the mass of the object and is constant for all objects, therefore, all objects fall with the same speed.

Explanation:

The weight of an object or force of gravity acting on an object on the surface of earth is a product of its mass and acceleration due to gravity.

Mathematically, w = mg

where, m=mass of the object; g = acceleration due to gravity

Also, from newton's law of gravitation, gravitational force on the object ,F = GMm/r²

where G is the gravitational constant; M is mass of Earth; m is mass of object; r is the distance of separation between the object and the center of mass of the earth which is approximately the radius of earth.

Since the weight of an object is equal to the force of gravitation acting on it

W = F

mg = GMm/r²

g = GM/r²

The expression above is that of the relationship between the force of gravity acting on a body on the earth's surface, the weight of that body and the acceleration due to gravity, g.

It can be seen that the acceleration due to gravity g is independent of the mass of the object. Therefore, the acceleration of objects due to gravity is constant for all objects and all objects fall with the same speed.

Answer:

The time of fall of an object is dependent only on the height of fall for a given acceleration due to gravity and it is independent of the object's mass

Explanation:

The gravitational force acting on an object on Earth can be observed as the weight, 'W', of the object which is a function of the mass, 'm', of the object and the relationship between the gravitational force and the mass of the object is given as follows;

W = m × g

Where;

g = The acceleration due to gravitational force = Constant

The relationship between the speed, 'u', and therefore, the time, 't', with which an object falls, the distance or height of fall, 'h', and the acceleration of the motion, 'g' is given as follows;

h = u·t + 1/2·g·t²

Given that the initial velocity of the object, 'u', of the object allowed to fall is u = 0 m/s, we have;

h = u·t + 1/2·g·t² = 0 × t + 1/2·g·t²

h = 0 × t + 1/2·g·t² = 1/2·g·t²

h = 1/2·g·t²

t² = 2·h/g

t = √(2·h/g)

Therefore, the time, 't', it takes every object to fall from a height, 'h', is dependent only on the height, 'h', for a given acceleration due to gravity, 'g' and it is independent of the mass, 'm', of the object.

In a sonometer by what change in linear density of wire its velocity becomes double? Keeping tension of wire constant

Answers

Answer:

Explanation:

In a sonometer , expression for speed of wave produced can be given as follows .

v = [tex]\sqrt{\frac{T}{m} }[/tex]

v is velocity , T is tension in wire , m is density per unit length .

Here v is inversely proportional to square root of m . So if m becomes m / 4

velocity changes as follows .

velocity = [tex]\sqrt{\frac{T}{\frac{m}{4} } }[/tex]

= [tex]\sqrt{\frac{4T}{m} }[/tex]

= 2v

velocity becomes two times . Hence to make velocity two times , mass per unit length  has to be changed to one fourth value , keeping tension constant .

What does vf stand for
a.fringe velocity
b.first velocity
c.final velocity

Answers

The correct answer is C. Final Velocity

Hope this helped!

All waves transmit energy. Only one type of wave does not require a medium to transmit energy. That is a _____wave?

A(compression
B(Electromagnetic
C(sound
D(water

Answers

Answer:

sound waves

Explanation:

jejehwherrbjwhsbwwbdbehej

sound because it’s that one

What is the main purpose of catabolism? to build up needed molecules in the body to produce energy for use by the body to remove built-up waste in the body.​

Answers

Answer:

to produce energy for use by the body.

Explanation:

Catabolism can be defined as a metabolic process which typically involves the breaking down of complex molecules (inorganic and organic) into smaller and simpler molecules. This metabolic process (catabolism) is always accompanied with the release of energy in the form of adenosine triphosphate (ADP).

Some examples of the complex molecules broken down through catabolism are proteins, nucleic acid, polysaccharides, and lipids; which are broken into the following smaller molecules, amino acids, nucleotides, monosaccharides, and fatty acids respectively.

Hence, the main purpose of catabolism in living organisms such as humans, animals and plants is to produce energy for use by the body.

Answer:

to produce energy for use by the body

Explanation:

Which arrow correctly indicates the direction of friction acting on the box?

Answers

Answer: [tex]F_4[/tex]

Explanation:

The friction opposes motion. We can assume the motion to be downwards because the only force is the weight of the box mgsin(theta) aka F3.

Arrow 4 correctly indicates the direction of friction acting on the box.

What is the friction force?

It is a type of opposition force acting on the surface of the body that tries to oppose the motion of the body. its unit is Newton (N).

Mathematically it is defined as the product of the coefficient of friction and normal reaction.

On resolving the given force and accelertaion in the different components and balancing the equation gets.

Friction is a force that resists motion. Because the only force acting on the box is its own weight, we may conclude it is moving downhill. As the force approach the downhill the friction force is acting opposite to it.

Hence, arrow 4 correctly indicates the direction of friction acting on the box.

To learn more about the friction force refer to the link;

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A crane lifts an air conditioner to the top of a building. If the building is 12 m high, and the air conditioner has a mass of 200 kg, how much work did the crane do to lift it? (Hint: the force the crane exerts is equal to the weight of the air conditioner)

Answers

Work needed = 23,520 J

Further explanation

Given

height = 12 m

mass = 200 kg

Required

work needed by the crane

Solution

Work is the transfer of energy caused by the force acting on a moving object  

Work is the product of force with the displacement of objects.  

Can be formulated  

W = F x d  

W = Work, J, Nm  

F = Force, N  

d = distance, m  

F = m x g

Input the value :

W = mgd

W = 200 kg x 9.8 m/s²x12 m

W = 23520 J

what is a frame of reference? how is it used to measure motion? ​

Answers

Answer:

When an object changes position with respect to a frame of reference, the object is in motion. Distance measures the path taken.

What is the standard mesurement unit of force A joule B Newton C degrees D meters

Answers

Answer:

B,Newton

Explanation:

I hope it helps

PLEASE HELP SOMEONE ASAPAPP!P

Answers

Balanced
Unbalanced
Balanced
Balanced (I think)
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