# Homework Help: What is the kinetic energy of object 1 after being pulled?

1. Oct 28, 2005

I'm not sure if I have these concepts correct for lab...

Two objects of different mass start from rest, are pulled by the same magnitude net force, and are moved through the same distance. The work done on object 1 is 500J. After the force has pulled each object, object 1 moves twice as fast as object 2.

a) How much work is done on object 2?
W1 = F1D1 = 500J thus
W2 = F1D1 = 500J

b) What is the kinetic energy of object 1 after being pulled?
Wnet = ∆K = .5mv^2 – 0 = 500J

c) What is the kinetic energy of object 2 after being pulled?
Wnet = ∆K = .5mv^2 – 0 = 500J

d) What is the ratio of the mass of object 1 to the mass of object 2?
Ob1: ∆K = .5m(2v)^2 = 4(.5mv^2)
Ob2: ∆K = .5m(1)^2 so...
1:4

Did I do this correctly? It seemed too easy...

2. Oct 29, 2005

### Diane_

Looks good to me. As far as it being easy, it only is if you understand the concepts with which you're dealing. Don't make problems any harder than they need to be.