• We’re currently investigating an issue related to the forum theme and styling that is impacting page layout and visual formatting. The problem has been identified, and we are actively working on a resolution. There is no impact to user data or functionality, this is strictly a front-end display issue. We’ll post an update once the fix has been deployed. Thanks for your patience while we get this sorted.

Physics: Conservation of momentum, 2d Collisions....HELP ME!!

Page 2 - Seeking answers? Join the AnandTech community: where nearly half-a-million members share solutions and discuss the latest tech.
Can someone answer these:

Had one question inthe lab i dont know what to put for: Why can u use projectile motion to investigate coservation of momentum in 2 dimensions?


And one more thing, if things are falling and moving forward at diffrent angles, isnt that momentum in 3 dimensions?
 
Doh. I can't read. You can use it if you're only talking about motion in the horizontal direction. I'm still not real clear what the question is asking. Do they mean firing a projectile into something else like shooting a bullet into a block of wood?
 
i think she means the part of the lab where the balls collide and fly off them as projectiles...mabey its more of a trick question..thanks thouhg
 
As long as you're only talking about a horizontal collision, you can. If there's any other component to the direction of the collision, you can't because then gravity is a net external force. In your lab, since the balls collided on a horizontal table top, that's fine. If you had done something like had them both roll down a ramp after colliding with one starting at rest, it wouldn't work.
 
hmm in my lab theres a ramp on the table and a stainary ball at the end of the ramp when u roll ball 1 down the ramp it hits the stationary ball, then they fly off the table..the ramp is set at the end..
 
As long as the ball is at the end of the ramp that's okay because the part horizontal and part vertical motion of the ball on the ramp gets turned into only horizontal motion as the instant of impact. I would have asked the prof to explain more about what they mean with a question like that because it's not very clear.
 
its impossible to look at motion as 3 dimentional. you will never draw a diagram of a problem from the front view instead of side view. if motion was in 3 dimentions it would mean the object is not moving in a straight line or a predictable curved line but more of a swirling line

you know that model of a DNA strand? 3 dimentional motion would be like if you have a ball rolling along 1 of the strandes. it would swirl around ya see?
 
actualy isnt it that momentum is always in 3 dimensions, i j k, but sometimes one or more are equal to 0? If an object is goin forward and down, at an angle, then its doin x, y and the angled projection is z. Flood5 also told me this..
 
HI, I think I am late but still let me share my views:
The question is indeed talking about 2D collision and not 3D!
You are expected to place the ramp on a table and place a board just below that on the ground. The ramp here acts as a launcher to give the ball an initial velocity. When the ball is released from the ramp, it follows projectile motion and from the equations of motion, you can easily traced down the initial velocity before collision. You will be making use of two ramps , placed at different orientation if two moving objects are required. Once the ball reach the board on the ground, the collision will be a 2D one! You have to trace out the path of the balls and calculate the velocity, and hence momentum after collision.
Hope i am clear!
Thanks!
 
I, DrPizza, do hereby declare that this thread is full of fail.

Oh, and in the OP, if there were no friction, the ball would not "roll."
 
You must log in or register to reply here.

TRENDING THREADS

Back
Top