Question

A bullet has a mass of 0.020 kg with an unknown initial velocity. A block of wood has a mass of 2.5 kg and is at rest. Following the collision, the masses are combined and have a final velocity of 1.2 m/s? What was the bullets initial velocity?

How would you set up the problem?

Group of answer choices

a) 0.020v + 2.5(1.2) = (0.020 + 2.5)(0)

b) 0.020(0) + 2.5v = (0.020 + 2.5)1.2

c) 0.020(1.2) + 2.5v = (0.020 + 2.5)(0)

d) 0.020v + 2.5(0) = (0.020 + 2.5)1.2

Answer 1

The correct setup to find the initial velocity of the bullet is equation d) 0.020v + 2.5(0) = (0.020 + 2.5)1.2, which uses the law of conservation of momentum.

Step-by-step explanation:

The student is asked to determine the initial velocity of a bullet before it collides with a block of wood based on the law of conservation of momentum.

The correct setup of the equation, given that momentum is conserved in a closed system, would be to equate the total momentum before the collision to the total momentum after the collision.

Therefore, the correct equation to represent this scenario is d) 0.020v + 2.5(0) = (0.020 + 2.5)1.2, where 'v' is the unknown initial velocity of the bullet.

To solve for 'v', you would isolate the variable on one side: 'v' = (2.520 * 1.2) / 0.020.