A 4.20-g bullet embeds itself in a 20.0-kg block, which is attached to a horizontal spring with a force constant of 950 N/m. The maximum compression of the spring is 2.10 cm. What is the speed of the bullet just before it hits the block?
A) 690 m/s
B) 700 m/s
C) 672 m/s
D) 900 m/s
E) 952 m/s

Question

Quizplus · Accepted Answer

The kinetic energy of the bullet-block system is converted into potential energy of the spring. Using conservation of energy: (1/2)mv^2 = (1/2)kx^2, solve for v. Here, m = 0.0042 kg + 20 kg, k = 950 N/m, x = 0.021 m.

A 420-G Bullet Embeds Itself in a 20