If the position vector of a particle is
$\vec r = - \cos \,t\hat i + \sin \,t\hat j - 18\,t\hat k$
then what is the magnitude of its acceleration ?
$0$
$1$
$sin^2\,t$
$cos\,t$
$Assertion$ : A tennis ball bounces higher on hills than in plains.
$Reason$ : Acceleration due to gravity on the hill is greater than that on the surface of earth
Two projectiles are thrown simultaneously in the same plane from the same point. If their velocities are $v_1$ and $v_2$ at angles $\theta _1$ and $\theta_2$ respectively from the horizontal, then answer the following question
The trajectory of particle $1$ with respect to particle $2$ will be
In the figure shown, the two projectiles are fired simultaneously. The minimum distance between them during their flight is ........ $m$
A rigid rod is sliding. At some instant position of the rod is as shown in the figure. End $A$ has constant velocity $v_0$. At $t = 0, y = l$ .
A particle starts from the origin at $t=0$ $s$ with a velocity of $10.0 \hat{ j } \;m / s$ and moves in the $x-y$ plane with a constant acceleration of $(8.0 \hat{ i }+2.0 \hat{ j }) \;m \,s ^{-2} .$
$(a)$ At what time is the $x$ - coordinate of the particle $16\; m ?$ What is the $y$ -coordinate of the particle at that time?
$(b)$ What is the speed of the particle at the time?