Question

A 12kW motor moves a 1000kg car at what constant velocity, if the motor applies a force that equals 2000N? Also, of the motor for 2.75s, what amount of work has the motor done on the car. (Show working out)

Answer 1

Given data

Power = 12 KW ,

mass (m) = 1000 kg ,

Force (F) = 2000 N ,

time (t) = 2.75 s

Determine

1. Velocity (v) = ?

2. Work (W) = ?

We know that Power (P) = Rate of doing work

= ( Work ÷time) KW

Also we know that Work = F × displacement

Force = m.a N

=> 2000 = 1000 × a

=> a = 2 m/s²

And we know that acceleration (a) = rate of change of velocity

= v ÷ t

=> v = a × t

= 2 × 2.75

= 5.5 m/s

Now determine the Power P = Work done ÷ time

12 = W ÷ 2.75

W= 12 ×2.75

= 33 KJ

= 33000 J