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Q31
(NDA-I/2022)
Science & Technology › Basic Science (Physics, Chemistry, Biology) › Basic mechanics concepts
Answer Verified
A boy of mass 52 kg jumps with a horizontal velocity of 2 m/s onto a stationary cart of mass 3 kg. The cart is fixed with frictionless wheels. Which one of the following would be the speed of the cart?
Result
Your answer:
—
·
Correct:
B
Explanation
The problem is solved using the principle of conservation of linear momentum, which states that the total momentum of a system remains constant if no external forces act on it. Linear momentum is defined as the product of mass and velocity (p = mv). In this scenario, a boy (m1 = 52 kg) jumps with a velocity (v1 = 2 m/s) onto a stationary cart (m2 = 3 kg, v2 = 0). This is a perfectly inelastic collision where the boy and cart move together with a common final velocity (V). The formula for final velocity is V = (m1v1 + m2v2) / (m1 + m2). Substituting the values: V = (52 * 2 + 3 * 0) / (52 + 3) = 104 / 55. This calculation yields approximately 1.89 m/s. Thus, the speed of the cart after the boy jumps on it is 1.89 m/s.
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