Newton’s Second Law corrected the old belief that force is needed to maintain motion. This idea came from the philosopher:
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Question
A woman throws an object of mass 500 g with a speed of 25 ms1.
- What is the impulse imparted to the object?
- If the object hits a wall and rebounds with half the original speed, what is the change in momentum of the object?
Short/Brief Note
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Solution
Mass of the object (m) = 500 g = 0.5 kg
Speed of the object (v) = 25 m/s
a. Impulse imparted to the object = Change in momentum
= mv – mu
= m(v – u)
= 0.5(25 – 0)
= 12.5 N-s
b. Velocity of the object after rebounds
= `- 25/2` m/s
v' = – 12.5 m/s
∴ Change in momentum = m(v’ – v)
= 0.5 (– 12.5 – 25)
= – 18.75 N-s
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