Question

A body of mass 10 kg is thrown up with a velocity 98 ms ! . Simultaneously another is dropped
from a tower. After 2 seconds their momenta are found to be same in magnitude. Then the mass of
the freely falling body is
1) 40 kg
2) 4 kg
3) 30 kg
4) 20 kg​

Answer 1

Answer:

40 kg

Explanation: Hello :)

Given:

m1 = 10kg

V1 = 98m/s

V' = velocity after 2 seconds

v' = 98 + (-10) 2 = 98 - 19.8 = 78.4m/s

momentum of m1

P1 = m1v'

= 10*78.4 = 784 kg.m/s

Now, m2= to be find

V2 = 0m/s (initaly)

v'' = velocity after 2 second

v'' = 9.8*2 = 19.6m/s

p2 = m2.v''

It is given that momentum of both body is same at 2 seconds

|p1| = |p2|

=> 784 = 19.6m2

=> m2 = 40

Hence, mass second body is 40kg