You are Here: Home >< Physics

# Velocity of ball after it leaves ramp, and after spring it contact is de-compressed? watch

1. http://www.chegg.com/homework-help/q...nchin-q1273254

I don't understand how to work out the velocity of the ball as it hits the floor. As it hits the floor, it's GPE becomes 0..so initial Energy (just spring PE) = final Energy (0 because the spring and the ball both lose their respective potentials, and the ball has no kinetic energy cos it's on the floor right?).

SO I am stuck :/

I have calculated the velocity of the ball when it leaves the launching ramp (and answer is ofc. in symbol form).
I thought KEinitial + PEinitial = KEfinal + PEfinal

KE + PE = 0.5mv^2 + (mgh + 0.5kx^2)

Initially, KE = 0 (nothing is moving..everything is at rest), and PE = 0.5kx^2 (the spring has PE because it is compressed).
So initial total energy = 0.5kx^2

Finally, KE = 0.5mv^2, and PE = mgh

So 0.5kx^2 = 0.5mv^2 + mgh

So (in an easier form) I have: mv^2 = kx^2 - 2mgh. I divide by m and then do square root to get the velocity. But how do I work out the velocity of the ball as it hits the floor?

Thank you

Edit: Apparently, the final answer for the velocity of the ball when it LEAVES THE RAMP does NOT depend on h... I am even more confused now
2. The initial energy of the ball is not just the pe in the spring. You need to add mgH
Take zero for gpe at the floor.
At the start you have eleastic pe + gpe
At the end you have no elastic pe, no gpe but lots of kinetic energy.

The velocity as it leaves the ramp is found (via the ke of the ball) from the initial epe in the spring less the gpe gained rising the height y.

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: April 18, 2013
Today on TSR

### Tuition fees under review

Would you pay less for a humanities degree?

### Can I get A*s if I start studying now?

Discussions on TSR

• Latest
Poll
Discussions on TSR

• Latest

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE