The upper half of an inclined plane of inclination $\text{θ}$ is perfectly smooth, whereas the lower half is rough. A block starting from rest at the top of the plane will again come to rest at the bottom. The coefficient of friction between the block and the lower half of the plane is

A $1 \mathrm{kg}$ block is being pushed against a wall by a force $F=75 \mathrm{N}$, as shown in the figure. The coefficient of friction is $0.25$. The magnitude of acceleration of the block is

A block of unknown mass is at rest on a rough, horizontal surface. A force $F$ is applied to the block. The graph in the figure shows its acceleration with respect to the applied force. The mass of the block is

A wooden block of mass $m$ resting on a rough horizontal table (coefficient of friction $=\mu$) is pulled by a force $F$, as shown in the figure. The acceleration of the block moving horizontally is:

A block of mass $M=5 \mathrm{kg}$ is resting on a rough horizontal surface for which the coefficient of friction is $0.2.$ When a pulling force $F=40 \mathrm{N}$ is applied, the acceleration of the block will be: $\left(g=10 \mathrm{m} {\mathrm{s}}^{-2}\right)$