# Question 5

A roller-coaster car of mass 200 kg, with the engine switched off, travels along
track ABC which has a rough surface, as shown in the diagram below. At point A,
which is 10 m above the ground, the speed of the car is 4 m·s-1.

At point B, which is at a height h above the ground, the speed of the car is 2 m·s-1.
During the motion from point A to point B, 3,40 × 103 J of energy is used to overcome
friction.

Ignore rotational effects due to the wheels of the car

5.1 Define the term non-conservative force. (2)

5.2 Calculate the change in the kinetic energy of the car after it has travelled from
point A to point B. (3)

5.3 Use energy principles to calculate the height h. (4)

On reaching point B, the car’s engine is switched on in order to move up the incline to
point C, which is 22 m above the ground. While moving from point B to point C, the car
travels for 15 s at a constant speed of 2 m·s-1, while an average frictional force of 50 N
acts on it.

5.4 Calculate the power delivered by the engine to move the car from point B to
point C. (5)

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