Chapter 8

NCERT
Class 9
Science
Solutions
17. How much momentum will a dumb-bell of mass 10 kg transfer to the floor if it falls from a height of 80 cm? Take its downward acceleration to be 10 ms–2.

Question:

How much momentum will a dumb-bell of mass 10 kg transfer to the floor if it falls from a height of 80 cm? Take its downward acceleration to be 10 ms–2.

Answer:

According to question,

m = 10 kg

s = 80 cm

   = 80/100m

a = 10 ms–2

u = 0

momentum P = ?

from the formula v2 = u2 + 2as

v2 = 0 + (2 x 10 x 0.80)

v2 = 16

v = √16

v = 4 m/s

∴ momentum P = mv

                       P = 10 × 4

                      P = 40 kg m/s

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