# Homework Help: Atwood machine - find kinetic energy

1. Nov 14, 2007

### NewJersey

1) Massess of 1.00kg and 1.01kg are suspended in a frictionless Atwood machine
a) Find acceleration of the 1.010kg mass
b) Find the total kinetic energy of the masses 2.50s after being released

So for a I set up an equation where a= (1.01-1.00)
1.00+1.010 times 9/87m/s
and got .0491 for accelaration is this right.

b) im confuse
Can anyone help

2. Nov 15, 2007

### rl.bhat

Find the velocity of each mass using vf = vi + at. Then find KE.

3. Nov 15, 2007

### NewJersey

so vf will equal
vf= (0.0491)*(3.8s)

Is part a right.

4. Nov 15, 2007

### andrevdh

part a is correct

5. Nov 15, 2007

### andrevdh

why do you take 3.8 seconds and not 2.50 seconds in the final speed calculation?

6. Nov 15, 2007

### NewJersey

SO KE= 1/2 mv
so i would plugged in 1/2 times the total mass? * vf

IS this right, I will calculate the numbers later

7. Nov 15, 2007

### andrevdh

Yes, but you need to square the speed.