physics Homework Help?

Question

A gun fires a bullet vertically into a 1.40-kg block of wood at rest on a thin horizontal sheet

 

If the bullet has a mass of 27.1 g and a speed of 230 m/s , how high will the block rise into the air after the bullet becomes embedded in it?

Answer 1

Step 1:

The mass of the block is .

The mass of the bullet is .

The initial speed of the bullet is .

The acceleration of gravity is .

The combined mass of the block with bullet is .

.

By conservation of momentum, Find the speed of the combined mass just after impact of the bullet.

.

Substitute , and .

.

Step 2:

Find the maximum height of the combined mass will rise into the air.

The kinetic energy of the combined mass just after impact is .

.

Potential energy of the combined mass is .

Law of conservation of energy: .

.

Solution:

The block rises to a height of into the air after the bullet becomes embedded.