# Kinematics Word Problem – Projectile Fired at a Stationary Vehicle

1. The problem statement, all variables and given/known data

A projectile is fired at a stationary vehicle. If the initial separation was 200m and the projectile travelled at a constant 75 m/s, find the acceleration the vehicle would need for a passenger to be able to reach out and calmly pull the projectile into the vehicle. (Assume the car starts accelerating at the same time as the projectile is fired). Let’s say the projectile is a bullet.

Car:
vi = 0 m/s
vf = 75 m/s
a=?
d=?
t=?

Projectile:
vi= 75m/s
vf= 75m/s
a= constant so 0m/s
t=?
d=?

2. Relevant equations

d=vit+1/2at2

v2=vi2+2ad

3. The attempt at a solution

So I’ve asked my physics teacher but he didn’t really help. He’s one of those stubborn teachers who you have focused on all your attention to him speaking. I’m not an auditory learner so I still don’t understand how to solve this problem. I just need a push on how to solve the problem.

distance of bullet = 200m + distance of car

I’ve tried to use the d=vt+.5at^2 equation and have both the car and bullet’s equation be t=t. I can’t find an appropriate formula for the bullet.

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