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As shown in the figure below, a box of mass m = 68.0 kg (initially at rest) is p

ID: 1448159 • Letter: A

Question

As shown in the figure below, a box of mass m = 68.0 kg (initially at rest) is pushed a distance d = 55.0 m across a rough warehouse floor by an applied force of FA = 210 N directed at an angle of 30.0° below the horizontal. The coefficient of kinetic friction between the floor and the box is 0.100. Determine the following. (For parts (a) through (d), give your answer to the nearest multiple of 10.)

(d) work done by the force of friction

Wf = ???J



(e) Calculate the net work on the box by finding the sum of all the works done by each individual force.

WNet = ???? J



(f) Now find the net work by first finding the net force on the box, then finding the work done by this net force.

WNet = ???? J

Explanation / Answer

d) work done by the friction = -((210*sin(30) + 68*10)*0.1)*55 = -785*.1*55 = - 4317.5 Joule

e) net work on box

work done by frictional force = -4317.5 J

work done by Fa = 210*cos(30)*55 = 10002.59 Joule

net work done = 5685.09 J

f)

Fnet = 210*cos(30) - (210*sin(30) + 68*10)*0.1 = 103.36

Wnet = 5685.09 J