Kinematics Word Problem - Projectile Fired at a Stationary Vehicle

AI Thread Summary
A projectile is fired at a stationary vehicle from an initial separation of 200 meters, traveling at a constant speed of 75 m/s. To determine the acceleration needed for the vehicle to allow a passenger to pull the projectile in, the distances traveled by both the vehicle and the projectile must be compared. The key equations involve the relationship between distance, time, and acceleration for both the vehicle and the projectile. By setting the velocities equal when the passenger can reach for the projectile, two equations can be formed to solve for the vehicle's acceleration and the time taken. This approach will provide the necessary solution to the problem.
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Homework Statement



A projectile is fired at a stationary vehicle. If the initial separation was 200m and the projectile traveled 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=?


Homework Equations



d=vit+1/2at2

v2=vi2+2ad


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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Wellesley1 said:

Homework Statement



A projectile is fired at a stationary vehicle. If the initial separation was 200m and the projectile traveled 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=?


Homework Equations



d=vit+1/2at2

v2=vi2+2ad


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.
Hello Wellesley1 . Welcome to PF !

How does the distance traveled by the bullet compare to the distance traveled by the vehicle ?
 
The passenger can pull the projectile into the vehicle, when his velocity is equal the velocity of the projectile. That gives you one equation. Difference between the distances traveled by the projectile and the vehicle is given. That gives you the second equation. Solving these two equations, you can find the acceleration and the time.
 
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