# Solve for the amount of force on an 8kg ball

• gigglin_horse
In summary: So the force exerted by the pillow on the ball would also be 32 N. In summary, when an 8kg ball rolling at 2m/s bumps into a pillow and stops in 0.5 seconds, the amount of force on the ball is 32 N. The force exerted by the pillow on the ball is also 32 N.
gigglin_horse

## 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

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...

## What is the formula for calculating force?

The formula for calculating force is F = m x a, where F is the force, m is the mass, and a is the acceleration.

## How do you determine the mass of an object?

The mass of an object can be determined by weighing it on a scale or using other measurement tools, such as a balance or mathematical calculations.

## What is the unit of force?

The unit of force is Newton (N). Other commonly used units include pounds (lb) and kilograms (kg).

## What is the acceleration of gravity on Earth?

The acceleration of gravity on Earth is approximately 9.8 meters per second squared (m/s²).

## Can you solve for force without knowing the mass?

No, the mass is a necessary component in the formula for calculating force, so it is not possible to solve for force without knowing the mass.

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