A block of wood of 1kg resting on an inclined plane a angle `30^@`, just starts moving down. If the coefficient of friction is 0.2, then find its velocity (in `ms^(-1)`) after 5s (take , g=`10ms^(-2)`)

Options

A. `16.45 ms^(-1)`
B. `15.35 ms^(-1)`
C. `16.35ms^(-1)`
D. `15.45ms^(-1)`

Answer

C

Explanation

For the motion of body along the incline.

Acceleration of block down the plane is given by
`a=(mg sin theta- mumg cos theta)/(m) " " (as, N=mgcostheta " and " f_s=muN)`
`10xxsin30^@ - 0.2 xx10cos30^@`
`10xx1/2-2xx(sqrt3)/(2) = 3.278 ms^(-2)`
From equation of motion , v = u + at velocity after 5s
`v=0+3.278xx5=16.35ms^(-1)`