Question

A dog  races up the stairs in a time of 1.80 seconds.  If the stairs are 12 feet high, how much power in hp is the dog putting out?  The weight of the dog is 48 lbs

Answer 1

The time taken by the dog to climb the stairs, t=1.80 s

The height of the stairs, h= 12 feet=3.66 m

The weight of the dog, m=48 lbs=21.77 kg

The work done by the dog in climbing up the stairs is,

`W=\text{mgh}`

Where g is the acceleration due to gravity.

On substituting the known values,

`W=21.77*9.8*3.66=780.85\text{ J}`

The power is given by,

`P=(W)/(t)`

On substituting the known values,

`P=(780.85)/(1.80)=433.80\text{ J/s}`

1 J/s = 1.34×10³ hp

Therefore,

`433.80\text{ J/s=433.80}*1.34*10^3\text{ hp=581.3}*10^3\text{ hp}`

Therefore the power put out by the dog is 581.3×10³ hp