# I had wrote that was because I was told that in the beginning of the spring being wound the PE=KE.

Can I check a concept question, The amount of work required to stop a moving object would be equal to the mass of the object times it intial speed due to mv^2 right. You need to apply the same kinetic energy to stop.

THe work done on a brake in stopping (force*distance) will be equal to the change in KE.

The homework question asks: which work woulf be required to stop a moving object: the intial speed, the intial kinetic energy of the object, the mass of the object times it acceleration, the mass of the object times its intials speed, or the square of the intial speed of the object.

Since you said its based on change in KE, The work required to stop the car would be intial KE

9 months ago

## To answer the concept question about the amount of work required to stop a moving object, you need to consider the definition of work and how it relates to the change in kinetic energy (KE) of the object.

Work (W) is defined as the product of force (F) and the displacement of the object (d) in the direction of the force. In this case, the force acting on the moving object is what brings it to a stop.

The equation for work is: W = F * d

When an object is in motion, it possesses kinetic energy. The amount of work required to stop the object is equal to the change in kinetic energy.

The equation for kinetic energy is: KE = 0.5 * m * v^2

Where m is the mass of the object and v is its velocity.

In order to stop the object, you need to decrease its velocity to zero (assuming it comes to a complete stop). This means the change in kinetic energy (Î”KE) is equal to the initial kinetic energy (KE_initial) of the object.

Therefore, the correct answer to the homework question "Which work would be required to stop a moving object?" would be the initial kinetic energy of the object.

To find the initial kinetic energy of the object, you need to know its mass and initial velocity. You can plug those values into the kinetic energy equation mentioned earlier to calculate the initial kinetic energy.

It's important to note that the other options provided in the homework question (such as the initial speed, the mass of the object times its acceleration, the mass of the object times its initial speed, or the square of the initial speed of the object) are not equivalent to the work required to stop the object. The correct answer is indeed the initial kinetic energy.