Question

Question #90503

Answer 1

`61.22N`

Explanation:

Refer to the figure below

As the mass slides down the inclined plane, we see that Normal reaction `N` is equal and opposite to the `cos theta` component of the weight. The other two forces acting on the mass are, `sin theta` component acting along the plane and force of friction acting up the plane and opposing the motion of the mass. _"net"

As there is movement in sliding down there is net force given as
`F_"net"=mgsin theta-f`
Using Newton's second law this net force can be written as

`F_"net"=ma` .......(1)
Where `m` is mass `and a` is acceleration produced.

Using the kinematic equation
`s=ut+1/2at^2` and inserting given quantities in SI units we get
`1.2=0xx0.42+1/2a(0.42)^2`
Solving for `a`
`a=1.2xx2/(0.42)^2 =13.605ms^-2`, rounded to three decimal places

Inserting value of `a` in (1)
`F_"net"=4.5xx13.605`
`=>F_"net"=61.22N`