At a metro station, a girl walks up a stationary escalator in $$20 \mathrm{~s}$$. If she remains stationary on the escalator, then the escalator take her up in $$30 \mathrm{~s}$$. The time taken by her to walk up on the moving escalator will be
Rain is falling vertically with a speed of $$12 \mathrm{~ms}^{-1}$$. A woman rides a bicycles with a speed of $$12 \mathrm{~ms}^{-1}$$ in east to west direction. What is the direction in which she should hold her umbrella?
One end of a string of length $$l$$ is connected to a particle of mass $$m$$ and the other to a small peg on a smooth horizontal table. If the particle moves in a circle with speed $$v$$, the net force on the particle (directed towards the centre) is ($$T$$ is the tension in the string)
A body is initially at rest. It undergoes one-dimensional motion with constant acceleration. The power delivered to it at time $$t$$ is proportional to