An open knife edge of mass $50 \ g$ is dropped from a height $2 \ m$ on a wooden floor. If the blade penetrates up to a depth of $10 \ cm$ into the wood,the average resistance offered by the wood to the knife edge is $....N$

$A$ body of mass $2 \, kg$ is released from point $A$. Its velocity at point $B$ is $4 \, m/s$,and it comes to rest at point $C$. The work done against friction is ............. $J$.

The velocity at which the $6 \text{ kg}$ mass (shown in the figure) strikes the ground when it is released from a height of $6 \text{ m}$ above the ground is . . . . . . $\text{m/s}$. Assume the pulley is massless and the string is light and inextensible. (Take $g = 10 \text{ m/s}^2$)

The work-energy theorem is valid in the presence of:

$A$ particle is acted upon by a force of constant magnitude which is always perpendicular to the velocity of the particle. The motion of the particle takes place in a plane. It follows that:

$A$ particle of mass $100 \ g$ is thrown vertically upwards with a speed of $5 \ m/s$. The work done by the force of gravity during the time the particle goes up is.....$J$