Question

A motorcar of mass 1200kg is moving along a straight line with a uniform velocity
of 90km/h. Its velocity is slowed down to 18km/h in 4s by an unbalanced external
force. Calculate the acceleration and the change in momentum. Also calculate the
magnitude of the force required.​

Answer 1

Answer:

Given:

Mass of the motor car, m = 1200 kg

Initial velocity of the motor car, u = 90 km/h = 25 m/s

Final velocity of the motor car, v = 18 km/h = 5 m/s

Time taken, t = 4 s

Solution:

ΔP = mv − mu

ΔP = 1200 × 5−1200×25 = −24000 kg m/s

v = u + at

5 = 25 + a × 4

⟹ a = −5 m/s2

(-ve shows retardation)

∣F∣ = m∣a∣ =1 200 × 5 = 6000 N

Explanation:

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