Question

Let's imagine a block on a sheet of ice, with negligible friction. The block has a mass of 5.00 kg. The block is currently moving to the right at 3.00 m/s. Let's say a rope is attached to this block, and it pulls horizontally on the block, also to the right, with a force of 12.0 N. With this force applied, the block moves a distance of 3.00 m to the right. How fast is the block moving at the end of this distance?

There is a lot of information in this problem, but let's think for a moment how to approach it.

We can use the work-kinetic energy theorem. That is, if we can find an initial kinetic energy, and find the work, we can then solve for the final kinetic energy. Knowing the final kinetic energy, we can find the final speed.

Let's first find the initial kinetic energy. What is the kinetic energy (in J) of the block when it is moving at 3.00 m/s?

Next, let's calculate the work (in J) done on the block by the rope.

J

Let's continue analyzing the example from the previous step.

Using the initial kinetic energy and work found in the previous step, what is the final kinetic energy (in J) of the block, after it has moved the 3.00 m distance?

J

Now that we have the final kinetic energy, use it and the mass of the block to solve for the final speed (in m/s).

m/s

Answer 1