Question

a force is applied on a car of mass 1500 kg so that its speed increases from 54 km/h to 72 km/h.find the work done by force on the car

Answer 1

     GIVEN,
                  u = 54 km/h = 54*5/18 = 15 m/s
                  v = 72 km/h = 72*5/18 = 20 m/s
                 m = 1500 kg
              kinetic energy = 1/2*m(v^2 - u^2)
                                         1/2*1500(20*20 - 15*15)
                                         750(400 - 225)
                                         750*175
                                         131250 J

Answer 2

Given:

Mass, m= 1500 kg
u = 54 km/h
= 54 × 5/18= 15 m/s
v= 72 km/h
= 72 × 5/18 = 20 m/s
W= K.E = ?

K.E = 1/2 m (v^2 - u^2)
= 1/2 × 1500 × (20×20- 15×15)
=750 × (400-225)
= 750 × 175
= 131250

K.E = 131250 J