(i) In the arrangement shown in the figure the coefficient of friction between the 2 kg block and the vertical wall is `mu= 0.5`. A constant horizontal force of 40 N keeps the block pressed against the wall. The spring has a natural length of 1.0 m and its force constant is `k = 400 Nm^(–1)`. What should be the height h of the block above the horizontal floor for it to be in equilibrium. The spring is not tied to the block.

(ii) A block of mass M is pressed against a rough vertical wall by applying a force F making an angle of `theta` with horizontal (as shown in figure). Coefficient of friction between the wall and the block is `mu = 0.75`.

(a) If F = 2 Mg, find the range of values of `theta` so that the block does not slide
[Take `"tan" 37^(@) = 0.75, "sin" 24^(@) = 0.4`]
(b) Find the maximum value of `theta` above which equilibrium is not possible for any magnitude of force F.

Answer

`theta le 13^(@)`
`37^(@)`