1. Question 5 (10 pts) If a horse really has 1.00 hp 746 w, then how fast can it make a 200. kg
wagon, initially at rest, move in 10.0 s? Ignore friction in the wagon, and assume a horizontal
surface, and assume that the horse can maintain this power for the entire 10.0 seconds. 12.2 m/s
B) 2.90 m/s C) 15.2 m/s D) 7.20 m/s E) 8.63 m/s A)
Solution
Let the maximum speed achieved be V m/s
Assuming constant acceleration ( since the hp is constant)
acceleration, a = V-0 / time = V / 10 m/s 2
distance covered in 10 seconds ( using v 2
- u 2
=2as ) ==> V 2
- 0 = 2*(V/10)*s ==> s = 5V
Work Done = Force * displacement ==> mass* acceleration * s = 200 * V/10 * 5V
Power = Work /time = 10V 2
This Power = 746 Watts
==> V = 8.6371 m/s