# I Need More Help

1. Oct 20, 2004

### rrastam

HERE IS ANOTHER qUESTION.....I GOT THE FIRST PART RIGHT BUT I CAN'T GET PART B RIGHT. PLEASE HELP
A 12-pack of Omni-Cola (mass 4.30 kg) is initially at rest on a horizontal floor. It is then pushed in a straight line for 1.60 m by a trained dog who exerts a horizontal force with magnitude 37.5 N.
(a) Use the work-energy theorem to find the final speed of the 12-pack if there is no friction between the 12-pack and the floor.
5.28 m/s
(b) Use the work-energy theorem to find the final speed of the 12-pack if the coefficient of kinetic friction between the 12-pack and the floor is 0.30.
? m/s

2. Oct 20, 2004

### Pyrrhus

Work energy Theorem

$$\sum W = \Delta K$$

$$W_{dog} - W_{friction} = \frac{1}{2}mv^2$$

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