If you hit a tennis ball over a net. When the ball reaches max height, it speed is?

Question

Options are: less than initial speed, g*t, equal to its initial, zero, greater than initial.

Answer 1

I think you have left off part of the question. The speed of a ball is a vector. When you hit the ball, the vector points upward and forward. Gravity pulls the vector downward. Small forces (air friction, etc.) retard the total speed, but assume those can be ignored.

At some point, the pull of gravity will pull the vector to point down instead of up. That's the maximum height. The horizontal component of the speed vector should not change (given our assumptions). It still goes forward at the initial velocity. However, The vertical component is instantaenously at zero. In a moment, the ball will start to accelerate vertically and the vector will continue to pull down below the horizontal line becuase of the force of gravity.

If this were not true, the ball would reach maximum height and then just drop from the sky (0 overall velocity) which you know it does not do.

So of your choices, probably equal to initial or ever so slightly les than initial would be the best.

The same thing happens if you drop, say, a ball from 10 feet and fire a bullet from a height of 10 feet. The both hit the ground at the same time.The fact that the bullet is speeding horizontally doesn't affect gravity pulling on it vertically. (yeah small effects like curvature of the Earth, wind resistance, etc. being ignored).

Answer 2

Less. The ball's speed relative to the ground is slowing down due to the resistance of the air.

Were you referring to the changing in height?

Answer 3

if you're saying that its zero..... then lemme tell you, its wrong...
it is certainly less than the initial speed....

only if a ball is hit up in the air (vertically up), then does the speed becomes zero at the max height

Cheers!

Answer 4

THE ANSWER IS IS NOT ZERO!!!
the ball doesn't stop because vertical speed is not affected by anything exept air resistance.

the answer is less than initial speed.

the ball would only stop if it was thown staight up

Answer 5

Do you EVER do your own homework? The only good thing is you've got all variations on a theme so you've either got to think about it or use a pin. In your case, I'd suggest a pin, you might end up pricking yourself but at tleast it'll stop your head hurting if you try to think.

Answer 6

the instantaneous velocity of the ball is less thant initial but not zero at the maximum height.


this can be explained better using calculus. do you require such an explanation?

Answer 7

Zero. It actually stops and then falls picking up speed again.

Answer 8

Zero.

Answer 9

less than its initial speed, if struck from "below"
the net-level

also, if taking air-resistance into acount,
"much" less than initial speed

Answer 10

zero at the top of the arc. it will go up slower and slower and slower, then for a milisecond it will stop, then start it's descent.