(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A 3kg body is at rest on a frictionless horizontal air track when a constant horizontal force F acting in the positive direction of an x axis along the track is applied to the body. The force F is applied to the body at t = 0 when the body is at the origin. A stroboscope records the position of the body at 0.5 s intervals. The readings are as follows.

Interval (I) 1: 0.04 m

I2: 0.2 m

I3: 0.44 m

I4: 0.8 m

How much work is done on the body by the applied force F between t = 0 and t = 2s?

2. Relevant equations

K = 1/2mv^2

W = [tex]\Delta[/tex]K

s = ut + 1/2at^2

v^2 = u^2 + 2as

3. The attempt at a solution

I really have no idea why I'm not getting the right answer. I can't see an error in what I've done.

1) Find a

u = 0

a = 2s/t^2

a = 2 x 0.04 / 0.5^2 = 0.32 ms^-2

2) Find v^2

v^2 = ((0 ms^-1)^2) + 2(0.32 ms^-1 x 0.8m)

3) Find the change in kinetic energy and hence the work done

[tex]\Delta[/tex]K = 1/2mv^2 = 1/2(3kg)(0.512m^2 s^-2) = 0.768 J

---

The answer is meant to be 0.96J. I think I might have done this question months ago but I cannot see where I have gone wrong in the least. Please point out any glaring mistakes :P.

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Mechanics - Work and Kinetic Energy question

**Physics Forums | Science Articles, Homework Help, Discussion**