Question

The velocity of a car increase from 54 km/hr to 72 km/hr. How much is the work done if the mass of the car is 1500kg?

Answer 1

w=change in k.e.=1/2*1500(20-15)

=750*5

=3750J

Answer 2

Answer:

Data : m = 1500 kg, u = 54 km/h

= 5400 m

_______ = 15 m/s,

3600s

v = 72 km/h = 72000m

_______ = 20m/s, W = ?

3600s

Work done,

W = increase in kinetic energy

= ½ mv² - ½ mu² = ½ m (v²-u²)

= ½ × 1500kg × [(20m/s)² - (15m/s)²]

= 750 × (400-225) J = 750×175 J

= 131250 J

The work done to increase the velocity of the car = 131250 J