Question

Starting from rest, a 2.1 times 10^-4 kg flea springs straight upward. While the flea is pushing off from the ground, the ground exerts an average upward force of 0.47 N on it. This force does 1.5 times 10^4 J of work on the flea. (a) What is the flea's speed when it leaves the ground? (b) How far upward does the flea move while it is pushing off? Ignore both air resistance and the flea's weight.

Answer 1

To find the flea's speed when it leaves the ground, we use the work-energy principle, and to find the distance the flea moves while pushing off, we use the work done by the ground.

Step-by-step explanation:

To answer part (a), we need to use the work-energy principle. The work done on the flea is equal to the change in its kinetic energy. The work done by the ground is equal to the force applied by the ground multiplied by the distance the flea moves while pushing off. So we have:

Work done on flea = Change in kinetic energy

0.47 N * d = (1/2) * (2.1 * 10^-4 kg) * v^2

Solving for v, we get:

v = sqrt((2 * 0.47 N * d) / (2.1 * 10^-4 kg))

To answer part (b), we can use the work done by the ground to find the displacement of the flea while pushing off. So we have:

Work done on flea = Force * Distance

0.47 N * d = 1.5 * 10^4 J

Solving for d, we get:

d = (1.5 * 10^4 J) / (0.47 N)