Comprehension # 1
If net force on a system in a particular direction is zero (say in horizontal direction) we can apply:
`Sigmam_(R )x_(R )= Sigmam_(L)x_(L), Sigmam_(R )v_(R )= Sigmam_(L)v_(L)` and `Sigmam_(R )a_(R ) = Sigmam_(L)a_(L)`
Here R stands for the masses which are moving towards right and L for the masses towards left, x is displacement, v is veloctiy and a the acceleration (all with respect to ground). A small block of mass `m = 1 kg` is placed over a wedge of mass `M = 4 kg` as shown in figure. Mass m is released from rest. All surface are smooth. Origin O is as shown.

At the same instant reaction on the wedge from the ground is ........N.

Options

A. `42.5`
B. `40`
C. `43.46`
D. None of these

Answer

A

Explanation

`N_(g) = N sin 30 + 40 rArr N_(g) = 42.5`