The following problem summarizes the ideas of work done on an object you studied
ID: 1547861 • Letter: T
Question
The following problem summarizes the ideas of work done on an object you studied in previous questions. A person holding a dog of mass 9 kg starts walking at time t=0s in a straight line for 5 m, then they walk up some stairs which have a length (not height) of 2.4 m and are placed at an angle 70 degree to the horizontal. the total amount of work done by the person on the dog is: What is the total power expended on the dog if the person walks at a constant speed of 0.93 m/s? What does the power equal in milli-horsepower unit?Explanation / Answer
a)
Work = m g h
= m g Lsin
= 9 * 9.8 * 2.4 *sin70o
= 198.9 J
(b)
Time = d /v = (2.4+5) / 0.93 = 7.956989 s
Power = W/ t
= 24.99 W
= 25 W
(c)
In mhp: (24.99689 W)(1 mhp / 0.746 W) = 33.5 mhp
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