Acceleration of a bouncing ball (no calculations needed)

In summary, the acceleration of a hard rubber ball being bounced on the floor is constant at 9.8m/s^2 while it is in the air, regardless of whether it is on its way down or its way back up. This is because the only force acting on the ball is gravity, and the initial force used by the thrower and the energy lost during the bounce do not affect the acceleration.
  • #1
Feodalherren
605
6

Homework Statement


A hard rubber ball is bounced on the floor. Compare the ball's acceleration on the way down to its acceleration on its way back up.


Homework Equations


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3. The Attempt at a Solution [/b
First off, ignore air resistance.
Lets assume that the person bouncing the ball uses some force and doesn't just drop the ball. This would mean that the acceleration of the ball would be
Initial force used + 9.8m/s^2, correct?

The bounce would absorb some of the initial force, but no all of it, correct?

The gravitational pull would be symmetrical so the end result would be

(Initial force - absorbed from bounce) + 9.8m/s^2, correct?
 
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  • #2
It's much simpler than you think.

What forces act on the ball after it leaves the person's hand and is on the way down?
What forces act on the ball after it bounces off the floor and is on the way up?
 
  • #3
All I can think of is gravity which would be symmetrical if you throw the ball up and wait for it to come down. Where I get confused is the bounce part. Doesn't the bounce make the ball lose some of it's energy?
 
  • #4
Feodalherren said:
Doesn't the bounce make the ball lose some of it's energy?
Sure, but so what? They are asking about the acceleration of the ball while it is in the air, not about the energy it has.
 
  • #5
also they are just asking about while it's going down and while it's going up, not about when it hits the ground
 
  • #6
Feodalherren said:
All I can think of is gravity
That is exactly right. While its going up and going down, the only force acting is gravity. So what must be the acceleration?
 
  • #7
a= 9.8 m/s^2

The force used by the thrower doesn't count because it only acted at the instant when the ball was thrown?
 
  • #8
Feodalherren said:
a= 9.8 m/s^2
Correct. (What direction is the acceleration?)
The force used by the thrower doesn't count because it only acted at the instant when the ball was thrown?
Exactly. As soon as the ball leaves the thrower's hand, the only force acting is gravity.

Same for the floor when it bounces: As soon as the ball leaves contact with the floor, the floor no longer exerts a force on the ball.
 
  • #9
Ah I see! The direction must be down. Thank you so much for clarifying :)!
 

Related to Acceleration of a bouncing ball (no calculations needed)

1. What factors affect the acceleration of a bouncing ball?

The acceleration of a bouncing ball is affected by the force of gravity, the surface it bounces on, and the elasticity of the ball itself. Other factors such as air resistance and spin also play a role.

2. Why does the acceleration of a bouncing ball decrease with each bounce?

As the ball bounces, energy is lost due to factors such as air resistance and the ball's elasticity. This results in a decrease in the height and speed of each subsequent bounce, leading to a decrease in acceleration.

3. Can the acceleration of a bouncing ball be negative?

Yes, the acceleration of a bouncing ball can be negative if it is thrown downward or if it bounces on a surface that is angled downward. This means that the ball is decelerating or slowing down as it bounces.

4. How does the height of the bounce affect the acceleration of a bouncing ball?

The height of the bounce does not directly affect the acceleration of a bouncing ball. The acceleration is determined by the initial velocity and the force of gravity. However, the height of the bounce can indirectly affect the acceleration through the factors that influence it, such as air resistance and elasticity.

5. Can the acceleration of a bouncing ball be constant?

No, the acceleration of a bouncing ball cannot be constant. As the ball bounces, energy is lost and the acceleration changes with each bounce. However, the acceleration can approach a constant value as the ball bounces fewer and fewer times and the energy loss becomes negligible.

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