Posted by Mota on .
A force of 100N pulls a box of weight 200N along a smooth horizontal surface makes 45(degree) to the floor .
Calculate the work done by the force.
A- in moving the box a distance of 25m along the horizontal.
B- against gravity.
C- against normal force.
Horizontal component = 100 cos 45 = 70.7
Work done by moving 25 m = 70.7*25 Joules
THE MOTION IS HORIZONTAL!!!
It does not move in the direction of gravity, thus zero
It likewise does not move in the direction of the normal force --> zero
This is a trick question intended to remind you that the work done is force IN THE DIRECTION OF MOTION times distance moved (also of course in the direction of motion)