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Question
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 plate. If the mass of the boy is 25 kg, what will be the new velocity of the bugghi ?
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Solution
It is given that:
Mass of the bugghi, mb = 200 kg
Velocity of the bugghi, Vb = 10 km/h
Mass of the boy, mboy = 25 kg
Velocity of the boy, VBoy = 4 km/h
Consider the boy and the bugghi as a system.
The total momentum before the process of sitting remains same after the process of sitting.
Using the law of conservation of momentum, we can write:
\[m_b V_b + m_{boy} V_{boy} = ( m_b + m_{boy} )V\]
\[ \Rightarrow 200 \times 10 + 25 \times 4 = (200 + 25) \times V\]
\[ \Rightarrow V = \frac{2100}{225} = \frac{28}{3} \text{ Km/h }\]
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