A. Just after it hits the ground
B. Exactly when it hits the ground
C. At the very top of its bounce
D. As soon as she drops it
3 answers
The correct answer is B. Exactly when it hits the ground.
At the moment the ball hits the ground, it comes to a stop, which means its velocity is zero at that instant. Since kinetic energy is calculated as \( \frac{1}{2}mv^2 \) (where \( m \) is mass and \( v \) is velocity), when the velocity \( v \) is zero, the kinetic energy is also zero. After hitting the ground, the ball will have zero kinetic energy just before it starts to compress and then begins to bounce back.
I apologize for any confusion. Let’s clarify the situation further regarding when the tennis ball has zero kinetic energy.
Option A: Just after it hits the ground — At this point, the ball is starting to compress and has not yet come to a complete stop, so it actually has some kinetic energy as it begins to rebound.
Option B: Exactly when it hits the ground — This is the moment the ball makes contact with the ground. The force of the impact causes it to decelerate, and while the speed decreases rapidly, there might still be a tiny amount of kinetic energy in play depending on how we define the exact moment.
Option C: At the very top of its bounce — At the very top of the bounce, the ball comes to a momentary stop before it starts to fall back down. This means it has zero kinetic energy at that instant.
Option D: As soon as she drops it — When the ball is dropped, it has gravitational potential energy but no kinetic energy until it starts falling.
Considering these points, the most accurate answer regarding when the ball has zero kinetic energy is C. At the very top of its bounce because that's the point where its velocity is momentarily zero before it starts descending again.
Thank you for your patience, and I appreciate the opportunity to correct that!
