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A ball is thrown vertically downward with a velocity of $20m/s$ from the top of a tower. It hits the ground after some time with a velocity of $80m/s$. The height of the tower is : $(g=10m/s_{2})$

The speed of a swimmer in still water is 20 m/s. The speed of river water is 10 m/s and is flowing due east. If he is standing on the south bank and wishes to cross the river along the shortest path the angle at which he should make his strokes w.r.t north is given by :

A particle moving with velocity $barV$ is acted by three forces shown by the vector triangle PQR. The velocity of the particle will :

Preeti reached the metro station and found that the escalator was not working. She walked up the stationary escalator in time $t_{1}$. On other days, if she remains stationary on the moving escalator, then the escalator takes her up in time $t_{2}$. The time taken by her walk up on the moving escalator will be:

The $x$ and $y$ coordinates of the particle at any time are $x=5t−2t_{2}$ and $y=10t$ respectively, where $x$ and $y$ are in meters and $t$ in seconds. The acceleration of the particle at $t=2s$ is:

If the velocity of a particle is $v=At+Bt_{2}$, where $A$ and $B$ are constants, then the distance travelled by it between $1s$ and $2s$ is