# What is the speed and mass of the object?

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The recoil of a projectile launcher finds that the linear momentum of an ejected object is 26.1 kg m/s, and the target is equipped with an energy detector that determines that the object has a kinetic energy of 200 J.

The recoil of a projectile launcher finds that the linear momentum of an ejected object is 26.1 kg m/s, and the target is equipped with an energy detector that determines that the object has a kinetic energy of 200 J.

##### 2 Answers

speed = 15.3256705

mass = 1.703025

#### Explanation:

From the Kinetic Energy and momentum formulas

and momentum

we can get

and we can get

because

so

for the speed, I will use

for the mass, I will use

By solving a system of equations.

#### Explanation:

We know the following based on the equations for momentum and kinetic energy.

To solve the above system of equations, we need to isolate a variable. **Let us first isolate mass to solve for velocity.**

**And because mass is equal we can combine the equations to solve for v.**

**Finally, we can solve for mass by plugging our velocity back in to the momentum equation** You could also find it other ways too.