A dise of mass 10 g is kept floating horizontally by throwing 10 marbles per secound against it from below . If mass of each marble is 5 g Calculate the velocity with which marbles are striking the disc . Assume that marbles strike the disc . Normally and rebound downwards with the same speed.

Options

A. `2.98 ms^(-1)`
B. `0.98 ms^(-1)`
C. `0.49 ms^(-1)`
D. `1.96 ms^(-1)`

Answer

B

Explanation

`F=(Deltap)/(Deltat) = Delta(mn v)/(Deltat)`

Here, m = mass of one marble = 5g
`n/(Deltat)=` number of molecules striking per second = 10
`Mg= m(n/Deltat)|Deltav|`
Here M = mass of disc
`(10 xx 10^(-3)(9.80) = (5 xx 10^(-3)(10)2v`
or `v = 0.98 ms^(-1)`