Ques
A skateboarder is cruising on his skateboard at 3 m/s and has a total mass of 70 kg. A friend jumps on
(from standing still). What is the new velocity of the skateboarder if the friend has a mass of 50 kg?

When a particle or a system of particles move in a system where no external force acts, then the total linear momentum of the particle system remains constant.

Explanation:

Given data:

Total mass of the skateboarder,

Mass of the friend,

Initial velocity of the skateboarder,

Initial velocity of the the friend,

Let the new velocity of the skateboarder when his friend jumps be .

From the conservation law of linear momentum,

double the distance = divide strength by 4

the chart show the masses and velocities of two colliding objects that stick together after a collision.

according to the law of conservation of momentum, the momentum of the object after the collision is  

answer

1,500

kg • m/s.