Chapter 8

NCERT
Class 9
Science
Solutions
15. An object of mass 100 kg is accelerated uniformly from a velocity of 5 ms–1 to 8 ms–1 in 6 s. Calculate the initial and final momentum of the object. Also find, the magnitude of the force exerted on the object.

Question:

An object of mass 100 kg is accelerated uniformly from a velocity of 5 ms–1 to 8 ms–1 in 6 s. Calculate the initial and final momentum of the object. Also find, the magnitude of the force exerted on the object.

Answer:

According to question,

m = 100 kg

t = 6 sec

u = 5 m/s

v = 8 m/s

initial momentum = mu

                             = 100 × 5

                             = 500 kg-m/s

final momentum = mv

                           = 100 × 8

                           = 800 kg-m/s

force exerted on the object = Change in momentum / Time taken

                                               = (800 - 500) / 6

                                               = 300 / 6

                                              = 50N

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