Work Energy and...

Mass of $B$ is four times that of $A . B$ moves with a velocity half that of $A$. Then, $B$ has 

A body of mass $15\ kg$ moving with a velocity of $10\ ms^{-1}$ is bought to rest. The work done by the brake is

The work done in placing a charge of 8$\times$${ 10 }^{ -18 }$ coulomb on a condenser of capacity 100 micro-farad is 

A bod of mass M is suspended by a massless string of length L.The horizontal velocity V at position A is just sufficient to make real the point B.The angle $\theta$ at which the speed of the bob is half of that it A satisfies:

A body of mass 1 kg begins to move under the action of a time dependent  force $\overrightarrow { F } =(2t\hat { i } +3t^{ 2 }\hat { j } )$ N, where $\hat { i }$ and $\hat { j }$ are unit vectors along x and y axes. What power will be developed by the force at the time t?

A particle is moving in a vertical circle. The tension in the string when passing through two positions at angles ${30}^{o}$ and ${60}^{o}$ from vertical (lowest position) are ${T}_{1}$ and ${T}_{2}$ respectively, then

A body of mass $2\ kg$ moving under a force has relation between displacement $x$ and time $t$ as $x=\dfrac{t^{3}}{3}$ where $x$ is in metre and $t$ is in sec. The work done by the body in first two second will be

Work done by a force $\vec{F}=(\hat{i}+2\hat{j}+3\hat{k})\ N$ action on a particle in displacing it from the point $\vec{r}_{1}=\hat{i}+\hat{j}+\hat{k}$ to the point $\vec{r}_{1}=\hat{i}-\hat{j}-2\hat{k}$

By applying a force $F=(3xy-5z) j +4zk$ a particle is moved along the path $y=x^2$ from point $(0,0,0)$ to the point $(2,4,0)$. The work done by the F on the particle is (all values are in SI units)

Two masses $10 \ gm$ and $40 \ gm$ are moving with kinetic energies in the ratio $9:25$. The ratio of their linear momentum is: