File Edit View History Bookmarks People Window Hawal Five-0 vdeo Puka x a Hamski
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File Edit View History Bookmarks People Window Hawal Five-0 vdeo Puka x a Hamski Nets Abara Ganb x Wi homework c D www.webassign.netweb/student/Assignment-Responsesnast?dep 15044192 7.00 (e) How much work was done by the person who pulled on the cord? -5 points YFs35.P 100. A truck engine transmits 31.0 kW (41.6 hp) to the driving wheels when the truck is traveling at a constant velocity of magntude 72.0 km/h (44.7 mWh) on a level road. (a) What is the resisting force acting (b) Assume that 63% of the resisting force is due to rolling friction and the remainder is due to air resistance. If the force of nolling friction of speed, and the force of air resistance is proportional to the square of the speed, what power wi drive the truck at 36.0 km/h? At 144.0 km/h? Give your answers v 36.0 km/h 144.0 km/h P Submit Answer Save Progress Practice Another Version Ask Your Previous Answers YF137 P009. 67 points figure), Assume that the size of the reck is small released from rest at point A, which is at the top edge of a large, hemispherical bowl wth radius R A small rock with mass 0.22 kg is particle, and assume that the rock slides rather than rons. The work done by fr ction on the rock when it moves from Point A to pont B at the to R, so that the rock can be treated as a bottom of the bowl has magnitude o.15 J.Explanation / Answer
1)
P = 31 kW = 31000 W
V = 72 km/h = 20 m/s
Power = force x speed,
total resisting force = 31000/20 = 1550N,
of which 976.5N (63%) is due to rolling friction and 573.5N (37%) is due to air resistance.
The rolling force is constant.
air resistance force is proportional to the square of speed, Fa = kv^2.
Fa = 573.5 = k x (20)^2
k = 1.43
now if the speed is reduced to 36km/h or 10 m/s then
Fa = 1.43 x (10)^2 = 143N
The total resistive force is now 976.5 + 143 = 1119.5N
So the total drive power is 1119.5 x 10 = 11.95 kW or 16 hp
2)
the speed is increased to 144km/h or 40m/s then,
Fa = 1.43 x (40)^2 = 2288 N
total force = 976.5 + 2288 = 3264.5N
total drive power = 130.58kW or 175 hp
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