# Need help with homework

1. Nov 24, 2005

### drod

a book falls off a bookshelf and hits the floor. given this info calculate the force of the book on the floor.
mass of the book 1.5kg the book touched the floor for .3 sec. the velocity of the book the moment the book hit the floor 3m/s.
the velocity of the book when it bounced off the floor 1m/s.

2. Nov 24, 2005

### mezarashi

Apply Newton's second law in the impulse form.

$$F \cdot \Delta t = m \Delta v$$

3. Nov 24, 2005

### mezarashi

Further explanation: This formula can be called the impulse equation. It says that a Force acting over some period of Time $$\Delta t$$ will create a change in momentum or velocity $$\Delta v$$.

Analyze the situation:
What is the change in the velocity of the book before and after impact?
How much time did it take for this change in velocity to happen?
Mass is given.

Can we then solve for force?