3.
A car of mass 800 kg is driven with its engine generating a power of 15 kW .
- The car is first driven along a straight horizontal road and accelerates from rest. Assuming that there is no resistance to motion, find the speed of the car after 6 seconds.
- The car is next driven at constant speed up a straight road inclined at an angle \(\theta\) to the horizontal. The resistance to motion is now modelled as being constant with magnitude of 150 N.
Given that \(\sin \theta = \frac { 1 } { 20 }\), find the speed of the car.
- The car is now driven at a constant speed of \(30 \mathrm {~ms} ^ { - 1 }\) along the horizontal road pulling a trailer of mass 150 kg which is attached by means of a light rigid horizontal towbar.
Assuming the resistance to motion of the car is three times the resistance to motion of the trailer. Find:
- the resistance to motion of the car,
- the magnitude of the tension in the towbar.
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