A car of mass 940.0 kg accelerates away from an intersection on a horizontal road. When the car speed is 42.5 km/hr (11.8 m/s), the net power which the engine supplies is 4300.0 W (in addition to the extra power required to make up for air resistance and friction). Calculate the acceleration of the car at that time.

0.39

Explanation:

Parameters given:

Mass of car, m = 940 kg

Speed of car, v = 11.8 m/s

Power supplied by engine, P = 4300 W

To get the acceleration, we must define the relationship between Power and velocity.

Power, P, is given in terms of velocity, v, as:

P = F * v

where F = force

This is because Power is given as:

(where E = energy. t = time taken, d = distance moved)

Force, F, is given as:

F = m*a

Therefore, Power will be:

P = m * a * v

Acceleration, a, will then be:

The acceleration of the car at that time is 0.39