$A$ trolley is sliding freely down an inclined plane as shown in the figure. The angle $(\alpha)$ that the string of the pendulum makes with the ceiling of the trolley is equal to ..........

$A$ man weighs $80\,kg.$ He stands on a weighing scale in a lift which is moving upwards with a uniform acceleration of $5\,m/s^2.$ What would be the reading on the scale? $(g = 10\,m/s^2)$ ............ $N$

$A$ man of weight $W$ is standing on a lift which is moving downward with an acceleration $a$. The apparent weight of the man is

The apparent weight of a body,when it is travelling upwards with an acceleration of $2 \ m/s^2$ and its mass is $10 \ kg$,will be ......... $N$.

$A$ wedge of height $H$ (fixed) and inclination $\alpha$ (variable) is moving on a smooth horizontal surface with constant acceleration $g \ m/s^2$. $A$ small block is placed at the bottom of the incline as shown in the figure, and it slips on the smooth surface of the incline. Choose the $CORRECT$ statement about the time taken by the block to reach the top of the incline.

An object of mass $2 \, kg$ is placed at rest in a frame $S_1$ moving with velocity $10 \hat{i} + 5 \hat{j} \, m/s$ and having acceleration $5 \hat{i} + 10 \hat{j} \, m/s^2$. The object is also seen by an observer standing in a frame $S_2$ moving with velocity $5 \hat{i} + 10 \hat{j} \, m/s$. Calculate the net force acting on the object with respect to the $S_2$ frame.