# What is the momentum and velocity of each ball after the....?

• j doe
In summary: What about momentum in the perpendicular direction?The total momentum of the two balls, in the original direction of motion of the first ball, is 35Ns, yes.
j doe

## Homework Statement

A 3.50 kg ball with a velocity of 10.00 m/s collides with a stationary ball with a mass of 5.00 kg. After the collision, the first ball travels at a 42.6 degree angle from its original path, while the second ball travels at a -26.7 degree angle from the other ball's original path.

1) What is the momentum of each ball after the collision?

2) What is the velocity of each ball after the collision?

## The Attempt at a Solution

1) p = 3.50 kg x 10.00 m/s = 35.00 Ns

2) v = (3.50 kg)(sin42.6) + (5.00 kg)(sin-26.7) = -8.44 m/s

I know that it's wrong, but I'm not sure how to solve these two problems. Can someone please help?

j doe said:
1) p = 3.50 kg x 10.00 m/s = 35.00 Ns
That is the initial momentum of ball 1.
j doe said:
2) v = (3.50 kg)(sin42.6) + (5.00 kg)(sin-26.7) = -8.44 m/s
kg and m/s are not the same. You cannot just exchange units like you want.

What is conserved in the collision?

mfb said:
That is the initial momentum of ball 1.
kg and m/s are not the same. You cannot just exchange units like you want.

What is conserved in the collision?
momentum is conserved and is the initial momentum what i need? how do i find the other ball's momentum?

You need the initial momentum, sure - as momentum is conserved, the final momentum will be the same. That gives you some relations for the speeds of the balls.

mfb said:
You need the initial momentum, sure - as momentum is conserved, the final momentum will be the same. That gives you some relations for the speeds of the balls.
i'm still really confused on how to solve this

j doe said:
i'm still really confused on how to solve this
Momentum is a vector, so has direction. The momentum you calculated has the direction of the original movement of the 3.5kg ball.
If after the collision the velocities are u and v, what is the momentum in that direction? What is the momentum perpendicular to that direction? What two equations can you write?

haruspex said:
Momentum is a vector, so has direction. The momentum you calculated has the direction of the original movement of the 3.5kg ball.
If after the collision the velocities are u and v, what is the momentum in that direction? What is the momentum perpendicular to that direction? What two equations can you write?
would you use m1v1=m2v2? and would the momentum of both of the balls be 35.00Ns?

j doe said:
would you use m1v1=m2v2? and would the momentum of both of the balls be 35.00Ns?
The total momentum of the two balls, in the original direction of motion of the first ball, is 35Ns, yes.
Write that as an equation with unknowns for the two speeds.
What about momentum in the perpendicular direction?

## What is momentum?

Momentum is a measure of an object's motion and is calculated by multiplying its mass by its velocity.

## What is velocity?

Velocity is the rate of change of an object's position with respect to time. It is a vector quantity that includes both magnitude and direction.

## What factors affect the momentum of a ball?

The momentum of a ball is affected by its mass and velocity. The greater the mass or velocity of the ball, the greater its momentum will be.

## How is momentum conserved in a collision?

Momentum is conserved in a collision, meaning that the total momentum of the system before the collision is equal to the total momentum after the collision. This is known as the law of conservation of momentum.

## What is the difference between linear and angular momentum?

Linear momentum refers to the motion of an object in a straight line, while angular momentum refers to the rotation of an object around an axis. Both are calculated by multiplying the object's mass by its velocity, but angular momentum also takes into account the object's moment of inertia and rotational speed.

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