Question

As shown in the figure below, a box of mass

m = 64.0 kg

(initially at rest) is pushed a distance

d = 80.0 m

across a rough warehouse floor by an applied force of

F_A = 222 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.)

(a)

work done by the applied force

W_A = 2739  J

(b)

work done by the force of gravity

W_g =   J

(c)

work done by the normal force

W_N =   J

(d)

work done by the force of friction

W_f = 40  J

(e)

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

W_Net =  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.

W_Net =  J

Answer 1

As per given data work done=force(222)xcos30x80=15380J. However, in part (a) it is given as 2739 J, which does not match with the calculated value.

Similarly, the friction force given in (d) is also not matching with the calculated value 50176J (frictionxmassxgxd=0.1x64x9.8x80).

(b) work done by the force of gravity= 222xcos90x80=0J

(c) Work done by normal force = 222xcos90x80=0J

(e) Net work on the box by finding the sum of all the works done by each individual force= 15380+50176=6555 J