# Force and Momentum

1. Dec 12, 2007

### JLPhysics

I wanted to post this in Homework but for some reason I can't.
Does anyone know the formulas for these problems?

An 82 kg man drops from rest on a diving board 3 m above the surface of the water and comes to rest .55 s after reaching the water. What force does the water excert on him?

A .40 kg soccer ball aproaches a football player horizontally with a velocity of 18 m/s to the north. The player strikes the ball and causes it to move in the opposite direction with a velocity of 22 m/s. What impulse was delivered to the ball bythe player?

A .50 kg object is at rest. A 3 N force to the right acts on the object during a time interval of 1.50 s. What is the velocity of this object at the end of this interval? At the end of this interval a constant force of 4 N to the left is applied for 3 s. What is the velocity at the end of the 3 s?

Last edited: Dec 12, 2007
2. Dec 13, 2007

### Staff: Mentor

One needs to show some work and effort when requesting assistance.

Here is a reference on impulse - http://hyperphysics.phy-astr.gsu.edu/hbase/impulse.html

In the first problem, an 82 kg man falls 3 m, so one calculates the kinetic energy by conservation of energy. From KE, one determines the velocity. Then in the water the man slows to rest (V=0) in 0.55 s.