Question

The speed of an object of mass 50kg increases from 54km/h to 108km/h.The change in momentum of the object is
(a)2700kgms-1

(b)750kgms-1

(c)450kgms-1

(d)2250kgms-1

Answer 1

Answer:

Correct option is

B

131250J

Initial Velocity, u=54km/hr=15m/s

Final velocity , v=72km/hr=20m/s

Mass =1500kg

Initial kinetic energy

2

1

mu

2

⇒

2

1

1500×15×15=168750J

Final kinetic energy

2

1

mv

2

⇒

2

1

1500×20×20=300000J

So, change in kinetic energy = work done=300000−168750=131250J