# Kinematics Word Problem - Projectile Fired at a Stationary Vehicle

• Wellesley1
In summary, the problem is to find the acceleration of a stationary vehicle that would allow a passenger to calmly pull a constantly moving projectile into the vehicle, when the initial separation between the two is 200m and the projectile travels at a constant speed of 75m/s. Two equations can be used to solve the problem: one equating the velocities of the passenger and projectile, and the other relating the distances traveled by each. The solution will give the vehicle's acceleration and the time it takes for the passenger to reach the projectile.
Wellesley1

## 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=?

d=vit+1/2at2

## 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.

Last edited:
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=?

d=vit+1/2at2

## 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.

## 1. What is kinematics?

Kinematics is the branch of physics that studies the motion of objects without considering the forces that cause the motion.

## 2. What is a projectile?

A projectile is any object that is launched into the air and continues to move under the force of gravity alone.

## 3. How do you solve a kinematics word problem?

To solve a kinematics word problem, you need to identify the given information, determine the variables involved, and use the appropriate equations to solve for the unknown variable.

## 4. How is a projectile fired at a stationary vehicle different from a regular projectile problem?

In a projectile fired at a stationary vehicle problem, there are two objects involved - the projectile and the stationary vehicle. This means that the initial velocity of the projectile will be affected by the velocity of the vehicle.

## 5. What are the key factors to consider in solving a kinematics word problem involving a projectile fired at a stationary vehicle?

The key factors to consider are the initial velocity of the projectile, the velocity of the vehicle, the time of the projectile's flight, and the distance between the projectile and the vehicle.

• Introductory Physics Homework Help
Replies
15
Views
2K
• Introductory Physics Homework Help
Replies
2
Views
3K
• Introductory Physics Homework Help
Replies
5
Views
970
• Introductory Physics Homework Help
Replies
2
Views
926
• Introductory Physics Homework Help
Replies
14
Views
5K
• Introductory Physics Homework Help
Replies
4
Views
910
• Introductory Physics Homework Help
Replies
6
Views
1K
• Introductory Physics Homework Help
Replies
1
Views
2K
• Introductory Physics Homework Help
Replies
6
Views
3K
• Introductory Physics Homework Help
Replies
15
Views
8K