When work is done on a body by an external force, its
Only kinetic energy increases
Only potential energy increases
Both kinetic and potential energies may increase
Sum of kinetic and potential energies remains constant
A small bar starts sliding down on inclined plane forming an angle $\theta $ with the horizontal. The friction coefficient depends on the distance $x$ covered as $\mu = kx$ , where $k$ is a constant. Find the distance covered by the bar till it stops
A particle which is experiencing a force, given by $\vec F = 3\vec i -12\vec j$, undergoes a displacement of $\vec d = 4\vec i$ . If the particle had a kinetic energy of $3\, J$ at the beginning of the displacement, what is its kinetic energy at the end of the displacement?
A child is swinging a swing. Minimum and maximum heights of swing from the earth's surface are $0.75\,m$ and $2\,m$ respectively. The maximum velocity of this swing is ............. $\mathrm{m}/ \mathrm{s}$
A mass of $M\ kg$ is suspended by a weightless string. The horizontal force that is displace it until the string makes an angle of $45^o $ with the initial vertical direction is
A particle is placed at the point $\mathrm{A}$ of a frictionless track $A B C$ as shown in figure. It is gently pushed toward right. The speed of the particle when it reaches the point $B$ is: $\left(\right.$ Take $g=10 \mathrm{~m} / \mathrm{s}^2$ ).