If a man increase his speed by $2 \,m/s$ , his K.E. is doubled, the original speed of the man is

Four particles $A, B, C, D$ of mass $\frac{\mathrm{m}}{2}, \mathrm{~m}, 2 \mathrm{~m}, 4 \mathrm{~m}$, have same momentum, respectively. The particle with maximum kinetic energy is:

A body initially at rest, breaks up into two pieces of masses $2 M$ and $3 M$ respectively, together having a total kinetic energy $E$. The piece of mass $2 M$, after breaking up, has a kinetic energy

A ball of mass $2\,kg$ and another of mass $4\,kg$ are dropped together from a $60$ feet tall building. After a fall of $30$ feet each towards earth, their respective kinetic energies will be in the ratio of

A particle of mass ${m_1}$ is moving with a velocity ${v_1}$and another particle of mass ${m_2}$is moving with a velocity ${v_2}$. Both of them have the same momentum but their different kinetic energies are ${E_1}$and ${E_2}$respectively. If ${m_1} > {m_2}$ then

A cylinder of $10 \,kg$ is sliding in a plane with an initial velocity of $10 \,m/s$. If the coefficient of friction between the surface and cylinder is $0.5$ then before stopping, it will cover. $(g = 10\,\,m/{s^2})$ ........ $m$