A 12.0 g bullet was fired horizontally into a 1 kg block of wood. The bullet initially had a speed of 250 m/s. The block of wood was hanging from a 2 m long piece of (massless) string. After the collision the block/bullet combined object swings upward on the string. Find the height the block/bullet combined object rises.

a. 0.66m
b. 0.45m
c. 0.12 m
d. 0.35 m
e. 0.27m

So height though which combination of block bullet rises is 0.45 m

Explanation:

We have given  mass of the bullet  

Velocity of the bullet

Mass of block of wood

Block is at rest so

From conservation of momentum.

From third equation of motion

So option (b) will be the correct answer.

work: w = fd (given)

work done by chet   =50*1 = 50 j

work done by mika =40*2 = 80 j

work done by sara =30*1.5 = 45 j

work done by bill =60*0.5 = 30 j

students in order from the greatest amount of work done to the least is mika> chet> sara> bill

hence option (b) is correct.