Solve for the amount of force on an 8kg ball

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Homework Help Overview

The problem involves calculating the force exerted on an 8kg ball that rolls at 2m/s and comes to a stop after colliding with a pillow over a duration of 0.5 seconds. Participants are exploring the relationship between force, momentum, and time in this context.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the application of momentum principles and the relationship between force and change in momentum. There are questions about the relevance of stopping time and the interpretation of forces involved in the collision.

Discussion Status

Some participants have provided calculations related to the force experienced by the ball and the implications of the pillow's role in stopping the ball. There is an ongoing exploration of the forces at play, with no explicit consensus reached on the final interpretation of the forces involved.

Contextual Notes

Participants express confusion regarding the concepts of momentum and force, particularly in relation to the stopping process and the forces exerted by the pillow. The discussion reflects a learning environment where foundational physics concepts are being examined.

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Homework Statement


"solve for the amount of force on an 8kg ball rolling at 2m/s when it bumps into a pillow and stops in 0.5 seconds."
...and...
"how much force does the pillow exert on the ball?"


Homework Equations


net momentum before = net momentum after?
Ft=(change in) mv?


The Attempt at a Solution


8kg x 2m/s = 16N of force...or 16 kg.m/s

but what's the stopping got to do with it?
isnt both halves of this question the same?
Im so confused :S

Please help
 
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F = ma = m*Δv/Δt
 


...That doesn't help me...

Sorry, I'm new to physics and don't understand a lot of it
 


Δ stands for change in something.

Δp is the change in momentum. You can also write that as m*Δv.

So initial momentum is 8 kg* 2 m/s.
Final p is 0. Δp = 16 then right?

The change in time Δt is just the .5 sec.

So F = Δp/Δt = 16 / .5 = ... ?
 


Ahhhhhh, I see.
32.
But what force does the pillow exert back?
Isn't it equal and opposite? But wouldn't that cancel?

Would it be 8N, but with no momentum?
 


32 N is the force on the ball to stop it.

By the statement of the problem it was from the pillow wasn't it?
 


Yeah, the pillow was the reason for the ball stopping...
 

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