A stone is tied to a string of length $L$ is whirled in a vertical circle with the other end of the string at the centre. At a certain instant of time, the stone is at its lowest position and has a speed $u.$ The magnitude of the change in its velocity as it reaches a position where the string is horizontal is
$u-\sqrt{u^{2}-2 g l}$
$\sqrt {2gL}$
$\sqrt {{u^2} - gL}$
$\sqrt {2({u^2} - gL)} $
Average velocity of a particle is projectile motion between its starting point and the highest point of its trajectory is : (projection speed = $u$, angle of projection from horizontal= $\theta$)
A body of mass $1 \,kg$ is projected from ground at an angle $30^{\circ}$ with horizontal on a level ground at a speed $50 \,m / s$. The magnitude of change in momentum of the body during its flight is ....... $kg ms ^{-1}$ $\left(g=10 \,m / s ^2\right)$
A particle is moving on a circular path of radius $r$ with uniform velocity $v$. The change in velocity when the particle moves from $P$ to $Q$ is $(\angle POQ = {40^o})$
A body slides down a frictionless track which ends in a circular loop of diameter $D$, then the minimum height $h$ of the body in term of $D$ so that it may just complete the loop, is
A projectile is thrown into space so as to have maximum horizontal range $R$. Taking the point of projection as origin, the coordinates of the points where the speed of the particle is minimum are-