Question

The engine of a bus of mass 5, 000 kg accelerate the bus from 2 m/s to 20 m/s in 120 seconds. The power expended by the bus is:

Answer 1

mark it as brainliest

Answer 2

Given :

Mass of the bus 'm' = 5000kg

Initial velocity 'u' = 2m/s

Final velocity 'v' = 20m/s

Time 't' = 120s

To find :

Power 'P' expended by the bus

Solution :

To find the power first we need to acceleration 'a', force 'F', displacement 's' and work 'W' from the given data.

• Acceleration = ($Final$ velocity - $Initial$ velocity) / Time

                      a = ($v - u$) / t

                         = (20m/s - 2m/s) / 120s = (18 m/s) / 120s

                     a = 0.15m/s²

• Force = mass x acceleration

               F = m x a

                  = 5000 kg x 0.15m/s²

              F = 750N

• From the equations of motion we know,

            Displacement = ($v^{2} - u^{2}$) / 2a

                                 s = [(20 m/s)² - (2 m/s)²)] / (2 x 0.15m/s²)

                                    = (396 m²/s²) / (0.3m/s²)

                                 s = 1320m

• Work = Force x Displacement

              W = F x s

                   = 750N x 1320m

               W = 990000Nm

• Power = Work / Time

                P = W / t

                   = 990000Nm / 120s

               P = 8250W

The power expended by the bus is 8.250kW