Why do objects bounce when considering momentum and Newton's third law?

  • Thread starter Stromthetroll
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In summary, the ball accelerates upwards because the force exerted on the mass center (compression) is greater than the force of gravity.
  • #1
Stromthetroll
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Why does an object bounce when speaking about momentum and Newton's third law
I would like to say it is because the upward force (the force the object falling enacts on the ground and the ground acts on the object) is greater than the force of gravity, which would be impossible in an object that is dropped not thrown. My second thought is that the momentum is greater in the falling object but would that cause it to bounce and if so why? I am not asking about the elasticity or the molecular structure just bouncing and how it relates to the third law.
 
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  • #2
Stromthetroll said:
Why does an object bounce when speaking about momentum and Newton's third law
I would like to say it is because the upward force (the force the object falling enacts on the ground and the ground acts on the object) is greater than the force of gravity, which would be impossible in an object that is dropped not thrown.

Welcome to PF.

Who says that the force the ground exerts on the object can't be greater than the force of gravity? The contact time can be very short.
 
  • #3
The force the ground exerts on the object is the same as the force the object exerts on the ground third law of motion the only force downward is gravity so all of it is exerted on the ground.
 
  • #4
Thanks for the welcome hopefully i don't have too many questions
 
  • #5
Stromthetroll said:
The force the ground exerts on the object is the same as the force the object exerts on the ground third law of motion the only force downward is gravity so all of it is exerted on the ground.
When the ball is at its lowest point (somewhat flattened onto the ground by the impact), the lower part of the ball is under compression. So the forces acting on the mass centre of the ball are gravity down and a compression force up. The forces at the ground are the same compression down from the ball and an equal reaction from the ground. Since this compressive force exceeds gravity the ball accelerates upwards.
 
  • #6
haruspex said:
When the ball is at its lowest point (somewhat flattened onto the ground by the impact), the lower part of the ball is under compression. So the forces acting on the mass centre of the ball are gravity down and a compression force up. The forces at the ground are the same compression down from the ball and an equal reaction from the ground. Since this compressive force exceeds gravity the ball accelerates upwards.

I did not even think of compression forces thank you for your aid.
 

FAQ: Why do objects bounce when considering momentum and Newton's third law?

What is bouncing?

Bouncing is the movement of an object that repeatedly hits a surface and then rebounds off of it.

What causes an object to bounce?

An object bounces due to the transfer of kinetic energy from the object to the surface it hits, causing it to rebound.

How does the surface affect bouncing?

The surface can affect bouncing by determining the amount of friction and elasticity present, which can impact the height and frequency of the bounces.

What factors affect the height of a bounce?

The height of a bounce can be affected by factors such as the elasticity of the object and surface, the force and angle of impact, and air resistance.

Can the height of a bounce be calculated?

Yes, the height of a bounce can be calculated using the coefficient of restitution, which measures the elasticity of the object and surface, and the initial height and velocity of the object.

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