- #1

- 194

- 0

And finally, for example, if two objects of different mass and different speed collide with each other and then stick together, how do you find their final velocity and in what direction?

- Thread starter ACLerok
- Start date

- #1

- 194

- 0

And finally, for example, if two objects of different mass and different speed collide with each other and then stick together, how do you find their final velocity and in what direction?

- #2

Doc Al

Mentor

- 45,011

- 1,288

To find the total momentum of a system, add the momenta of each object. Remember that momentum is a vector, so learn to add vectors.Originally posted by ACLerok

Right now we're studying momentum and impulse. I know how to find momentum and impulse but how do you find the total magnitude of momentum in a system? How about the change in momentum?

Also, Δmomentum = momentum

And finally, for example, if two objects of different mass and different speed collide with each other and then stick together, how do you find their final velocity and in what direction?

But, talk is cheap. The only way to learn this stuff is by doing a bunch of problems. Get busy!

- #3

- 194

- 0

Thanks!

- #4

Doc Al

Mentor

- 45,011

- 1,288

There are at least two ways to add vectors. You can break them into components, and add the components of each. TheOriginally posted by ACLerok

To add vectors you square both components (or all three if z is involved) and take the square root of the some of them correct?

R = √(R

But you also have to find the direction of the resultant vector.

The other way is to draw the arrows and add them directly, using trig. Sometimes that's easier.

- #5

- 194

- 0

k i understand.. the direction and angle can be found just by finding the arctan of the y component divided by the x component. thanksOriginally posted by Doc Al

There are at least two ways to add vectors. You can break them into components, and add the components of each. Themagnitudeof the resultant is found as you state:

R = √(R_{x}^{2}+ R_{y}^{2})

But you also have to find the direction of the resultant vector.

The other way is to draw the arrows and add them directly, using trig. Sometimes that's easier.

- #6

- 194

- 0

Thanks

- #7

Doc Al

Mentor

- 45,011

- 1,288

As far as after the collision, that depends on the kind of collision. Was it elastic? (Did it bounce back up to the original height?) If so, energy is conserved. If it has the same speed just after the collision, what about its velocity and momentum?

Remember that momentum and velocity are

- #8

- 194

- 0

- #9

Doc Al

Mentor

- 45,011

- 1,288

How high does it bounce? If you know that, you can figure out how fast it left the ground. For example, if it doesn't bounce at all, all the KE is lost: its speed after the collision is zero. (Think of dropping a lump of putty.)Originally posted by ACLerok

Momentum conservation has nothing to do with it; we're talking about energy conservation.