6) A car of mass 1200 kg accelerates from rest to a speed of 8.0 m s-1 in a time of 2.0 s
a) Calculate the forward driving force acting on the car while it is accelerating
Assume that, at low speeds, all frictional forces are negligible,
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b) At high speeds the resistive frictional force F produced by air on a body moving
with velocity v is given by the equation F=bvº, where b is a constant.
1 Derive the base units of force in the Sl system
(2)
il Determine the base units of b in the SI system
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ili The car continues with the same forward driving force and accelerates until it
reaches a top speed of 50 m 5-1. At this speed the resistive force is given by the
equation F by 2. Determine the value of b for the car.
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iv Sketch a graph showing how the value of F varies with v over the range 0 to 50 m
3-1. Use your graph to describe what happens to the acceleration of the car during
this time
[4)