Question

3. A 400 gram block is attached to a spring, with a spring constant of 900 N/m. The spring is compressed by 30.0 cm and then is released. Find the speed of the block when the spring returns to its normal state. Assume that the surface is frictionless.

9. In a ballistic pendulum, find the speed of a bullet if the mass of the bullet is 40 grams and the mass of the block is 2.00 kg and rise to 20 cm height.

Answer 1

Potential energy provided to the spring will convert into kinetic energy of the block so we can write it as

Speed of the block when spring return to its normal state is 14.23 m/s

------------------------- Solution of Question 9 ----------------------

Using conservation of momentum we can write

momentum is conserved before and after collision

------------- equ(1)

Now using energy conservation we can write

Kinetic energy = potential energy

---------------- equ(2)

using equation 1 and 2 we get

or

using this relation we can calculate speed of bullet as

So the speed of the bullet is 100.975 m/s