Question

58. Two bodies of masses 4kg and 16kg are at
rest. The ratio of times for which the same force
must act on them to produce the same kinetic
energy in both of them is
1) 1:4 2) 2:1 3) 1:2 4) 4:1​

Answer 1

Answer:

kinetic energy is given by: 

so taking velocity for mass 1kg as v1, we get

and taking velocity for mass 4kg as v1, we have

given that e1=e2,

equating the above terms and simplifying, we get,

now , momentum is given by,

let us assume ,p1 as momentum for mass 1kg and p2 for mass 4kg

so ,

p1=1×v1

and p2=4×v2

then, p2p1=41=1:4

Hence,

option (A) is correct answer.