Catholic High Prelims 2004 P2 Q4
A toy car is given a brief push which sends it along a horizontal section of a runway. The car moves down the ramp as shown in the figure below.
(a) Draw labelled arrows on the diagram to show the 3 forces acting on the car at A.
(b) The length of the ramp is 0.90 m and the average force of friction is 0.11 N. The car has 0.30 J of kinetic energy at the top of the ramp and loses 0.50 J of potential energy as it moves from the top to the bottom of the ramp.
(i) Calculate the work done by the car against friction as it moves down the ramp.
(ii) Calculate the kinetic energy of the car at the bottom of the ramp.
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Answer:
(a)
(b)
(i)
Work done = f * d
= 0.11 * 0.90 J
= 0.099 J (2 s.f.)
= 9.9 * 10-2 J
(ii)
Kinetic energy of the car = initial KE + loss in GPE - energy loss due to frictional forces
= 0.30 J + 0.50 J - 0.099J
= 0.70 J (2 s.f.)
