As a warm-up for their juggling act, two clowns are tossing balls straight up in the air and catching them. While following the balls with his eyes, Joey says, ”Isn’t it strange how they just stand still in the air for a moment before they fall back down?” ”Nonsense”, says Charlie, ”they never stand still, it’s just that there is no acceleration at the top of the path.

Question

As a warm-up for their juggling act, two clowns are tossing balls straight up in the air and catching them. While following the balls with his eyes, Joey says, ”Isn’t it strange how they just stand still in the air for a moment before they fall back down?” ”Nonsense”, says Charlie, ”they never stand still, it’s just that there is no acceleration at the top of the path.

a) Is Joey right? Explain why, or why not.
b) Is Charlie right? Explain why, or why not.

Answer 1

Aaaarrrgghhhhh !!!!!

Joey is right. At the top v = 0, no velocity except that of mother earth spinning on her axis and making her way around the sun.
The acceleration is constant, -9.81 m/s^2 the whole time.
Charlie could not possibly, any way, be more wrong. Send him to his room !!!