A bullet is fired through a wooden board with a thickness of 8.0 cm. The bullet
ID: 1405402 • Letter: A
Question
A bullet is fired through a wooden board with a thickness of 8.0 cm. The bullet hits the board perpendicular to it, and with a velocity of +350 m/s. The bullet then emerges on the other side of the board with a velocity of +210 m/s. Assuming constant acceleration (rather, deceleration!) of the bullet while inside the wooden board, calculate the acceleration. (Note that the positive velocities define the positive direction to be in the bullet's direction or travel.)
2. Calculate also the total time the bullet is in contact with the board (in sec)
Explanation / Answer
Here ,
a) initial velocity , u = 350 m/s
final velocity , v = 210 m/s
distance , d = 0.08 m
Using third equation of motion
v^2 - u^2 = 2 *a * d
210^2 - 350^2 = 2 * a * 0.08
solving for a
a = -4.9 *10^5 m/s^2
the acceleration of bullet is -4.9 *10^5 m/s^2
b)
using first equation of motion
v = u + a*t
210 = 350 -4.9 *10^5 * t
t = 2.86 *10^-4 s
the total time of contact is 2.86 *10^-4 s
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