A ball is projected from ground at an angle of $\theta $ from horizontal then graph of kinetic energy and time will be

A rifle bullet loses $1/20^{th}$ of its velocity in passing through a wooden plank. The least number of planks required to stop the bullet is :-

A block of mass $m$ is sliding on a fixed frictionless concave surface of radius $R$. It is released from rest at point $P$ which is at a height of $H \ll R$ from the lowest point $Q .$

$(a)$ What is the potential energy as a function of $\theta$, taking the lowest point $Q$ as the reference level for potential energy?

$(b)$ What is the kinetic energy as a function of $\theta$ ?

$(c)$ What is the time takes for the particle to reach from point $P$ to the lowest point $Q$ ?

$(d)$ How much force is exerted by the block on the concave surface at the point $Q$ ?

Two bodies of different masses ${m_1}$ and ${m_2}$ have equal momenta. Their kinetic energies ${E_1}$ and ${E_2}$ are in the ratio

Write the definition of work and kinetic energy.

The adjoining diagram shows the velocity versus time plot for a particle. The work done by the force on the particle is positive from