A 5-kg object slides down a frictionless surface inclined at an angle of 30º from the horizontal.The total distance moved by the object along the plane is 10 meters.The work done on the object by the normal force of the surface is
A)zero
B)0.50 kJ
C)0.43 kJ
D)0.58 kJ
E)0.25 kJ

Question

Quizplus · Accepted Answer

Since the surface is frictionless, the only force acting on the object is its weight which acts down the plane. The component of the weight acting along the plane is given by:

w(sin30º) = (5 kg)(9.8 m/s^2)(0.5) = 24.5 N

Since the object is sliding down the plane, the displacement and the direction of the weight are the same. Therefore, the work done by the weight force on the object is given by:

W = Fd = (24.5 N)(10 m) = 245 J

However, the normal force of the surface is acting perpendicular to the displacement, so the work done by this force is zero.

Thus, the work done on the object by the normal force of the surface is zero, so the answer is A) zero.

A 5-Kg Object Slides Down a Frictionless Surface Inclined at an Angle