Elastic collision with the floor

In summary, the conversation discusses a ball of mass 100g falling from a height of 5.2m and colliding elastically with the floor. The questions ask for the height the ball reaches after the collision, as well as the impulse and average force during the collision. The conversation also mentions using momentum to calculate these values.
  • #1
dttah
37
0

Homework Statement


A ball of mass m = 100g , falls at an height of 5,2m and it collides elastically with the floor and comes up again. Find the height h2 (how much the ball has come up), the impulse, the average force if the collision lasts 0,02seconds.


Homework Equations





The Attempt at a Solution



I got the velocity just before the collision:
mgh = 1/2mv^2 => v = square root of (2gh) => v = 10m/s.
Okay, now I don't understand how I can find the height. If it was a completely elastic collision it'd still be 5,2 meters, but I guess it's not because it is actually asking to find it.

About the impulse and the average force I know how to find them, but I'd need the height first.
Thanks.
 
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  • #2
From the wording of this question I would agree with you. 'Elastically' means KE before = KE after and this means the ball should go to the same height as long as air resistance can be ignored. There is no mention of air resistance so... I agree with you.
You do not need the height to calculate impulse and average force. You need to use ideas about momentum for that.
 
  • #3
Okay, sounds good to me. Thanks.
 

Related to Elastic collision with the floor

1. What is an elastic collision with the floor?

An elastic collision with the floor refers to a scenario where an object collides with the floor and bounces back with the same energy it had before the collision. In other words, the kinetic energy is conserved and there is no loss of energy during the collision.

2. How is an elastic collision with the floor different from an inelastic collision?

In an inelastic collision with the floor, the object loses some of its energy and does not bounce back with the same velocity it had before the collision. This is because some of the energy is converted into other forms, such as heat or sound. In an elastic collision, the object retains all of its kinetic energy and bounces back with the same velocity.

3. What factors affect the elasticity of a collision with the floor?

The elasticity of a collision with the floor depends on the materials involved and the speed and angle of the object's impact. Generally, harder and more rigid materials will result in a more elastic collision, while softer and more flexible materials will result in a less elastic collision.

4. Can an elastic collision with the floor occur in real-world scenarios?

Yes, elastic collisions with the floor can occur in real-world scenarios. For example, a bouncing ball or a trampoline are both examples of elastic collisions where the object bounces back with the same energy it had before the collision.

5. How is the coefficient of restitution related to elastic collisions with the floor?

The coefficient of restitution is a measure of the elasticity of a collision. It is defined as the ratio of the relative velocity of separation to the relative velocity of approach. In an elastic collision with the floor, the coefficient of restitution would be equal to 1, indicating a perfectly elastic collision. However, in real-world scenarios, the coefficient of restitution is usually less than 1 due to factors such as air resistance and friction.

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