# How would I solve this? (Mass and speed)

1. Nov 19, 2014

### GracieBridger

How would I work out how fast a mass of 790kg would have be travelling to move a mass of 1523kg?

It's been a long time since I've done physics so any help would be great.

Thanks guys!

2. Nov 19, 2014

### UVCatastrophe

We need more information -- is the smaller mass colliding with the larger one? If so, is the collision elastic or inelastic? Or is the smaller mass pulling the larger one? Is there friction involved? Etc..

3. Nov 19, 2014

### GracieBridger

Hey mate the smaller mass is colliding with the larger one. The friction would be semi damp Tarmac which from what I've looked at already is 0.8?
I can't remember anything about technical terms in physics.
Basically I want to know how fast my car(pug 107-790kg) would have to travel to shunt the vehicle infront(vectra- 1524kg) if it was at a complete stand still.

4. Nov 19, 2014

### jbriggs444

Asked and answered in the general physics forum. Damp tarmac will drop the coefficient of friction down well below 0.8. The answer there was based on an assumption of dry pavement.

5. Nov 20, 2014

### ChrisVer

1, Suppose you have the 1523kg mass attached to the 790kg mass by a (very strong) rope and you start moving, then by the moment the 790kg mass will move the 1523 will also move...you will just need more power because you move a mass of ~1523+790 kg.

2. Suppose you want to crash into that 1523kg mass car with yours... then you just need to hit it... even with a very small velocity, you are going to give the other car some portion of it, depending on your cars' masses ratio ... if you want to give some certain velocity to the 1523kg car, then you just have to ask about it.