If air is blown very fast into the vertical hole of a spool of thread, a card laid flat against the other end does not fall. Why?

A thin rod of length L and mass M is held vertically with one end on the floor and is allowed to fall. Find the velocity of the other end when it hits the floor, assuming that the end on the floor does not slip?

A metre stick is held vertically with one end on the floor and is then allowed to fall . Find the speed of the other end when it hits the floor , assuming that the end of the floor does not slip . Take g = 10 m/ s^(2) . [sqrt30 m//s]

A meter stick is held vertically with one end on the floor and is allowed to fall. The speed of the other end when it hits the floor assuming that the end at the floor does not slip is (g=9.8 m//s^(2))

A ladder 10 metres long rests with one end against a vertical wall, the other on the floor. The lower end moves away from the wall at the rate of 2 metres/minute. The rate at which the upper end falls when its base is 6 metres away from the wall

Take a piece of thread. Tie a small piece of stone to one end of the thread. Hold the other end of the thread in hand and whirl it round. Note the motion of the stone. If the thread breakes suddenly, the stone files off along tangent to the circle at the instant. Read the above passage and answer the following question: (i) which force is whirling the stone ? who is providing this force ? (ii) why does the stone fly off along the tangnet to the circle at that instant? (iii) what value of life do you learn from this?

A rod of length 2 m is held vertically with one of its end on the floor. It is then allowed to fall. Calculate the speed of the other end when it strikes the floor. Assume that the end of the rod which is on the floor does not slip.

Answer the following: a) The casing of a rocket in flight burns up due to friction. At whose expense is the heat required for burning obtained? The rocket or the atmosphere? b) Comets move around the sun in highly elliptical orbits. The gravitational force on the comet due to the sun is not normal to the comet's velocity in general. Yet the work done by the gravitatonal force over every complete orbit of the comet is zero. Why? c) An artificial satellite orbiting the earth in very atmosphere loses its energy grdually due to dissipation against atmospheric resistance, howerver small. Why then does its speed increase progressively as it comes closer and closer tothe earth? d)In fig i) the man walks 2m carrying a mass of 15 kg on his hands. In Fig ii) he walks the same distance pulling the rope behind him. The rope goes over pulley, and a mass of 15 kg hangs at its other end. In which case is the work done greater?