Two blocks A and B each of mass m are placed on a smooth horizontal surface. Two horizontal force F and 2F are applied on blocks A and B, respectively, as shown in fig. Block A does not slide on block B. Then then the normal reaction acting between the two blocks is (assume no friction between the blocks)

Options

A. F
B. `(F)/(2)`
C. `(F)/(sqrt3)`
D. `3 F`

Answer

D

Explanation

Acceleration,
`a = (2F - F)/(m + m) = (F)/(2 m)` (towards left)
Horizontal force on `B` given the equation,
`2F - N sin 30^(@) = m . a`
or `2F - (N)/(2) = m((F)/(2m))`
`:. N = 3F`