A dog is climbing down into a well to drink water. In each jump it goes down 4 steps. The water level is in 20th step. How many jumps does the dog take to reach the water level?

Figure shows water in a container having 2.0-mm thick walls made of a material of thermal conductivity 0.50Wm^(-1)C^(-1) . The container is kept in a melting-ice bath at 0^(@)C . The total surface area in contact with water is 0.05m^(2) . A wheel is clamped inside the water and is coupled to a block of mass M as shown in the figure. As the goes down, the wheel rotates. It is found that after some time a steady state is reached in which the block goes down with a constant speed of 10cms^(-1) and the temperature of the water remains constant at 1.0^(@)C .Find the mass M of the block. Assume that the heat flow out of the water only through the walls in contact. Take g=10ms^(-2) .

The area of cross section of a large tank is 0.5m^2 . It has an opening near the bottom having area of cross section 1cm^2 . A load of 20 kg is applied on the water at the top. Find the velocity of the water coming out of the opening at the time when the height of water level is 50 cm above the bottom. Take g=10ms^-2

Spherical shaped marbles of diameter 1.4cm each, are dropped into a cylindrical beaker of diameter 7cm containing some water. Find the number of marbles that should be dropped into the beaker so that the water level rises by 5.6cm.

A block of wood is floating on water at 0^(@)C with a certain volume 'V' above the water level. The temperature of water is slowly raised to 20^(@)C . How does the volume 'V' change with the rise in temperature ?

A student had a breakfast of 200 food calories. He thinks of burning this energy by drawing water from the well and watering the trees in his school. Depth of the well is about 25 m. The pot can hold 25 L of water and each tree requires one pot of water. How many trees can he water? (Neglect the mass of the pot and the energy spent by walking. ("Take g" = 10 ms^(-2))

Read the paragraph and answer the following question: You must be knowing about the high and low tides that occur regularly in the sea. The level of the sea water at any given location along sea shore increase and decreases twice a day at regular intervals. High and low tides occur at different times at places. The level of water in sea changes because of the gravitational force exerted by the moon. Water directly under the moon gets pulled towards the moon and the level of water there goes up causing high tide at that place. At two places on the earth at 90^(@) from the place of high tide, the level of water is minimum and low tides occur there. How many times the sea level at the coast change?

A boat takes 1.6 hours longer to go 36kms up a river than down the river. If the speed of the water current is 4 km per hr, what is the speed of the boat in still water?