A truck with a mass of 1.5 x 103 kg accelerates to a speed of 18.0 m/s in 12.0 s from a dead stop. Assume that the force of resistance is a constant 400.0 N during the acceleration. What is the average power developed by the truckÍs engine?
Power = Net Force x velocity Net force = driving force - force of resistance Driving force = mass x acceleration Acceleration = (final velocity - initial velocity) / time Acceleration = (18 - 0) / 12 = 1.5 m/s² Driving force = 1.5 x 10³ x 1.5 = 2250 N Net force = 2250 - 400 = 1850 Power = 1850 x 18 = 3.33 x 10⁴ Watts
There are several information's already given in the question. Based on those information's the answer can be easily deduced. Mass of the truck = 1.5 x 10^3 kg Constant force of resistance = 400 N Final Velocity = 18 m/s Initial velocity = 0 m/s Time taken = 12 s Then Acceleration = (Final velocity - initial velocity)/Time = 18 /12 = 3/2 = 1.5 m/s^2 Then Driving force = Mass * Acceleration = 1.5 * 10^3 * 1.5 = 2250 N So Net Force = 2250 - 400 = 1850 N Average power developed = 1850 * 18 = 3.33 * 10^4 W
