# How Do You Calculate the Final Speed of a Rocket Car on an Inclined Ramp?

• canucks81
In summary, the problem involves a 1200 kg rocket car on a 100 meter long ramp inclined at 10°. The rocket exerts a force of 8300 N for 5.70 seconds and then shuts down. The question asks for the speed at the end of the ramp, assuming no friction. The solution involves using the equation vf = vi + at and subtracting the distance traveled when the engine shuts down from the total ramp length to find the remaining distance. Then, using the new distance and the formula vf^2 = vi^2 + 2ad, the final speed of the rocket car is calculated to be 28.8 m/s.
canucks81

## Homework Statement

A 1200 kg rocket car is placed at the bottom of a 100 meter long ramp inclined at 10°. The rocket is turned on and it exerts a force of 8300 N for 5.70 seconds, and then it shuts down. Find the speed with which the rocket car leaves the ramp (assume frictionless).

## Homework Equations

http://img98.imageshack.us/img98/9425/54fl1.png

## The Attempt at a Solution

http://i.imgur.com/MGDp7Rf.png?1

I didn't show all of my solution but I need to know if that part is correct. What I did next is I assumed vi = 0 and the used the formula vf = vi + at which gave me an answer of 29.7 m/s, however, the correct answer is 28.8 m/s.

Last edited by a moderator:
You've calculated the max speed. Did you use the ramp length?

What do I do with the ramp length? I didn't use it.

You're asked for the speed at the end of the ramp, not the speed when the engine shuts down.

So would I calculate the distance traveled up to when the engine shuts down, then subtract it from the length of the ramp to find the remaining distance?

That'll work.

I'm not sure how to get the new acceleration from when the engine shuts down. I know that it has to be negative because the rocket will slow down.

## What is the "Dynamics rocket car problem"?

The Dynamics rocket car problem is a physics problem that involves calculating the motion of a car powered by a rocket engine. It is often used as an example to demonstrate the principles of Newton's laws of motion.

## What are the main components of the problem?

The problem involves a car that is propelled by a rocket engine, a launch ramp, and the force of gravity. Other factors such as air resistance and friction may also be considered depending on the specific problem.

## How is the motion of the car calculated?

The motion of the car can be calculated using Newton's laws of motion. The first law states that an object will remain at rest or in uniform motion unless acted upon by an external force. The second law states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. The third law states that for every action, there is an equal and opposite reaction.

## What are some common assumptions made in solving this problem?

Some common assumptions made when solving the Dynamics rocket car problem include neglecting air resistance, assuming a constant acceleration throughout the motion, and assuming that the rocket engine provides a constant thrust.

## What are some real-world applications of this problem?

The Dynamics rocket car problem has real-world applications in the design and testing of rockets and other vehicles that use propulsion systems. It can also be used to analyze the motion of projectiles and to understand the effects of forces on moving objects in general.

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