Question

A body of mass m=10−2 kg is moving in a medium and experiences a frictional force F=−kv2. Its initial speed is v0=10 ms−1. If, after 10 s, its energy is 1 8 mv0 2, the value of k will be :
(1) 10−3 kg m−1
(2) 10−3 kg s−1
(3) 10−4 kg m−1
(4) 10−1 kg m−1 s−1 please the solution of this fast

Answer 1

ur answer is in attachment

Answer 2

Answer:

10^-4kg/m

Explanation:

kf/ki=1/8mv^2/1/2mv^2

=1/4

vf/vi=1/2

vf=v/2

-kg^2=mdv/dt

integral of dv/v^2=integral of -kdt/m

[-1/v] =-K/m t

1/v -2/v =K/m t

-1/v = K/ m t

K=. m/ v t

= 10^-2/10*10

= 10 ^-4 kg/ m