Egyptian pyramid workers push a 1200-kg block up an incline that has an angle of 69 degrees to the vertical,at a constant speed of 0.5 m/s.The coefficient of kinetic friction between the block and the incline surface is 0.44.How much power must the workers supply? A)3.1 $\times$ 10² W B)9.3 kW C)4.5 kW D)7.9 kW E)2.4 kW

Question

Quizplus · Accepted Answer

We can begin by finding the force required to push the block up the incline. The force parallel to the incline is given by:
Fpar = m*g*sin(69°) = 1200*9.81*sin(69°) = 11647.7 N

There is a frictional force opposing the motion given by:
Ffric = μ*m*g*cos(69°) = 0.44*1200*9.81*cos(69°) = 5046.7 N

The net force required to maintain constant speed is:
Fnet = Fpar - Ffric = 11647.7 - 5046.7 = 6601 N

The power required is the product of force and velocity:
P = Fnet*v = 6601 * 0.5 = 3300.5 W ≈ 4.5 kW

Therefore, the answer is choice C.

Egyptian Pyramid Workers Push a 1200-Kg Block Up an Incline ×\times×

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