# A mass and a frictionless ramp

1. Nov 8, 2007

### physicsperson

1. The problem statement, all variables and given/known data
Well i have a tiny question here

a 2 kg mass starts at rest and slides down a 10 m high, 15 m long frictionless ramp. At the bottom of the ramp it reaches a flat surface where it hits and sticks to a stationary 3 kg mass . Find the final speed of the masses after collision.

2. Relevant equations
mgh = .5mv^2

3. The attempt at a solution

i was just wondering does the 15 m really matter, where do i use it. I understand the second momentum part of the question but i dont understand what i am supposed to do with the 15 m. All i did was mgh = .5mv^2 and substituted height and mass to get velocity. Please Help.

2. Nov 8, 2007

### andrevdh

Maybe it is not a head on collision in which case the angle is required?

3. Nov 8, 2007

### rl.bhat

When the mass slides down the frictionless ramp, its accelarion is not g but g*sin(theta) where theta is the angle of the ramp to the horizontal. And you can find sin(theta) by using length and height of the ramp.

4. Nov 8, 2007

### physicsperson

thanks

thanks for the help, actually i just omitted the length and used energy equations, and i got the right answer...go figure..