# Can any of you guys help to understand kinetic energy?

1. Apr 16, 2012

### suryanarayan

can any of you guys help to understand kinetic energy???

when we apply kinetic energy conservation...should we split the velocity into two components???
eg)))))
two blocks of mass m are connected by a spring and are both given a velocity v at an angle of 45 degree with the horizontal(they lie on the horizontal)
..assuming no friction is present...
what will be the maximum elongation of the spring??

i used by equating 1/2 k x2 with the initial ke of the two masses along the horizontal i.e.vcos45???is it correct???pls help me(no vertical motion)

2. Apr 16, 2012

### wotanub

Re: can any of u guys help to understand kinetic energy???

Well energy is a scalar so it it's meaningless to split the KE into two components.

You should however find the component of the force that gave the initial velocity in order to find the elongation.

3. Apr 16, 2012

### suryanarayan

Re: can any of u guys help to understand kinetic energy???

can you pls tell me how to to solve it then...or did i do it correctly???

Last edited by a moderator: Apr 16, 2012
4. Apr 16, 2012

### wotanub

Re: can any of u guys help to understand kinetic energy???

I'm confused by the problem. How can the velocity be at a 45 degree angle with the horizontal if the masses must move only on the horizontal?

5. Apr 16, 2012

### suryanarayan

Re: can any of u guys help to understand kinetic energy???

they are both given a horizontal velocity v......its given like that in the question...dont know why

6. Apr 16, 2012

### wotanub

Re: can any of you guys help to understand kinetic energy???

In that case, I'd work it as you did.

$2 \frac{1}{2} m (vcos(45°))^{2} = \frac{1}{2}k(Δx)^{2}$