# Projectile Kinetic Energy and Recoil in Spring Gun Experiment

• CoreanJesus
In summary, the conversation discusses a problem involving a projectile fired from a spring gun at rest on a frictionless surface. The combined mass of the gun and projectile is given as M2 and the kinetic energy of the projectile after firing is K. The solution involves using the formula for kinetic energy and considering the conservation of momentum to find the final velocity of both the gun and projectile. The final answer is given as (M1/(M2-M1))K.
CoreanJesus

## Homework Statement

A projectile of mass M1 is fired horizontally from a spring gun that is initially at rest on a frictionless surface. The combined mass of the gun and projectile is M2. If the kinetic energy of the projectile after firing is K, the gun will recoil with a kinetic energy equal to...

## Homework Equations

this is part of the problem.
I know you need the kinetic energy formula but I don't get the other formula.

## The Attempt at a Solution

Hi,

You will need to take into consideration that the total momentum is conserved.

CoreanJesus
But what should the initial momentum be? 0?

Yes, the initial momentum is zero. That does not mean that the final velocity of the gun and of the projectile will be also zero. Do not forget that velocity (and momentum too) is a vector. So if you have two velocities (or momentum) in the opposite directions, you need to subtract one velocity from the other.

CoreanJesus
so M1V1=(M2-M1)V2
K=.5M1V1^2
KE=.5(M2-m1)V2^2 and plugin?

DoItForYourself
Exactly.

CoreanJesus
Thank you so much!

## What is a projectile from a spring gun?

A projectile from a spring gun is an object that is launched through the air by the force of a compressed spring. It can be any small object such as a ball or a pellet.

## How does a spring gun work?

A spring gun works by compressing a spring using a lever or other mechanism. When the trigger is pulled, the spring is released, propelling the projectile forward with a great amount of force.

## What factors affect the trajectory of a projectile from a spring gun?

The trajectory of a projectile from a spring gun is affected by a few key factors, including the initial speed of the projectile, the angle at which it is launched, and the force of gravity acting on it.

## What is the maximum range of a projectile from a spring gun?

The maximum range of a projectile from a spring gun depends on the initial speed and angle of launch. Generally, the higher the initial speed and the greater the angle of launch, the farther the projectile will travel.

## Can a projectile from a spring gun be lethal?

Depending on the force of the spring and the type of projectile used, a projectile from a spring gun can potentially be lethal. It is important to always use caution and proper safety measures when handling and using a spring gun.

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