A bullet fired straight through a board 0.10 m thick strikes the board with a speed of 480 m/s and emerges with a speed of 310 m.

Part A

What is the x component of the average acceleration of the bullet while in the board? The positive x direction is the initial direction of motion of the bullet.

Express your answer with the appropriate units.

givens

vf = 310 m/s

vi = 480 m/s

d = 0.1 m

formula

vf^2 = vi^2 + 2*a*d

Solution

310^2 (m/s) ^2 = 480^2 (m/s) ^2 + 2 * a * 0.1 meters

96100 = 230400 + 2*a * 0.1

96100 - 230400 = 2*a*0.1

-134300 = 2*0.1*a

-134300 = 0.2 * a

-134300/0.2 = a

a = - 671500 m/s^2

The important thing to notice is that the acceleration is minus which means the bullet is slowing down.