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

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Homework Help Overview

The discussion revolves around the mechanics of bouncing objects, specifically in the context of momentum and Newton's third law. Participants explore the relationship between forces acting on a falling object and the ground, questioning how these forces contribute to the phenomenon of bouncing without delving into elasticity or molecular structure.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants discuss the forces involved when an object impacts the ground, questioning whether the upward force can exceed gravitational force. There are attempts to clarify the relationship between the forces exerted by the object and the ground, as well as the role of compression forces during impact.

Discussion Status

The conversation is ongoing, with participants providing insights into the mechanics of bouncing. Some have offered clarifications regarding the forces at play, while others have expressed gratitude for the guidance received. Multiple interpretations of the forces involved are being explored.

Contextual Notes

There is an emphasis on understanding the forces without considering elasticity or molecular aspects, which may limit the scope of the discussion. Participants are navigating assumptions about the nature of forces during the bouncing process.

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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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.
 
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.
 
Thanks for the welcome hopefully i don't have too many questions
 
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.
 
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.
 

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