a window washer uses a stick to push a 0.7kg rag upward along a window. the stic

Question

a window washer uses a stick to push a 0.7kg rag upward along a window. the stick exerts a constant force of 12 newton's on the rag at an angle of 30 degrees to the vertical. the coefficient of friction between the rag and the glass is 0.4. find the acceleration of the rag and the time it take  
s for the rag to move 2 meters up the glass starting from rest.

a window washer uses a stick to push a 0.7kg rag upward along a window. the stick exerts a constant force of 12 newton's on the rag at an angle of 30 degrees to the vertical. the coefficient of friction between the rag and the glass is 0.4. find the acceleration of the rag and the time it takes for the rag to move 2 meters up the glass starting from rest.

Explanation / Answer

Here ,

the normal force , N = 12 * sin(30)

N = 6 N

friction acting , f = 0.4 * 6

f = 2.4 N

Now, let the acceleration of the rag is a

Using second law of motion ,

0.7 * a = 12*cos(30) - 2.4 - 0.7 *9.8

a = 2.05 m/s^2

the acceleration of the rag is 2.05 m/s^2

Now ,

for d = 2 m

using second equation of motion ,

2 = 0*t + 0.5 * 2.05 * t^2

t = 1.4 s

the time taken to travel 2 m is 1.4 s

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