$A$ block of mass $m$ is in contact with the cart $C$ as shown in the figure. The coefficient of static friction between the block and the cart is $\mu$. The acceleration $\alpha$ of the cart that will prevent the block from falling satisfies:

$A$ very broad elevator is going up vertically with a constant acceleration of $2\,m/s^2$. At the instant when its velocity is $4\,m/s$,a ball is projected from the floor of the lift with a speed of $4\,m/s$ relative to the floor at an elevation of $30^{\circ}$. The time taken by the ball to return to the floor is $..............\,s$ $(g=10\,m/s^2)$.

Find the apparent weight of a body of mass $1.0 \,kg$ falling with an acceleration of $10 \,ms^{-2}$. $\left(g \approx 10 \,ms^{-2}\right)$

$A$ ball is dropped from an elevator moving upward with acceleration '$a$' by a boy standing in it. What is the acceleration of the ball with respect to the boy and the ground respectively? [Take upward direction as positive]

$A$ body of mass $2 \, kg$ is hung on a spring balance mounted vertically in a lift. If the lift descends with an acceleration equal to the acceleration due to gravity $g$,and if the lift moves up with a constant velocity of $2 \, m/s$,the reading on the balance will be ......... $kg$.

$A$ car is moving on a circular horizontal track of radius $10 \,m$ with a constant speed of $10 \,m/s$. $A$ bob is suspended from the roof of the car by a light wire of length $1.0 \,m$. The angle made by the wire with the vertical is (in rad)