A car is driven at a constant speed of 79 km/h down a road. The car's engine delivers 47 kW of power. Calculate the average force that is resisting the motion of the car.
To calculate the average force resisting the motion of the car, we can use the following equation:
Power (P) = Force (F) x Velocity (v)
In this case, the power delivered by the car's engine is given as 47 kW and the velocity of the car is 79 km/h. However, we need to convert the velocity to meters per second (m/s) to match the standard unit of power (watts).
First, let's convert the velocity from km/h to m/s:
1 km/h = 1000 m/3600 s
So, 79 km/h = (79 * 1000) m/3600 s = 79000 m/3600 s ≈ 21.944 m/s
Now, we can rearrange the equation to solve for force:
F = P / v
F = 47,000 W / 21.944 m/s ≈ 2141 N
Therefore, the average force resistance to the motion of the car is approximately 2141 Newtons.