In a typical Indian Bugghi (a luxury cart drawn by horses), a wooden plate is fixed on the rear on which one person can sit. A bugghi of mass 200 kg is moving at a speed of 10 km/h. As it overtakes a school boy walking at a speed of 4 km/h, the boy sits on the wooden plate. If the mass of the boy is 25 kg, what will be the new velocity of the bugghi?

Ans.

Initial momentum of the school boy before sitting = 4×25

= 100 kg km/h

Initial momentum of the bugghi before the boy sat on it

= 10×200 = 2000 kg km/h

Total initial momentum of the bugghi and the school boy

= 2000+100 = 2100 kg km/h

Let the new velocity of the bugghi be v km/h.

Final momentum of the bugghi after the school boy sat on it

= v×(100+25)

= 125v kg km/h

Applying conservation of total linear momentum,

⇒ 125v = 2100

∴ The new velocity of the bugghi after the process of sitting = 28/3 km/h