Take a plastic boat and make a hole at this rear end. Inflate a balloon and fix it on the hole in the boat. Release the boat in water. What happens to the boat as the air in the balloon escapes slowly? Why?

Apparatus: Glass bottle, baloon, hot water, etc. : Procedure: Fix a balloon on the mouth of a glass bottle. Hold this bottle in hot water. What happens?

Take two rubber balloons. Fill one with water and blow air into the other. Now prick both balloons with a pin. What do you observe ?

Bring ‘active dry yeast’ from the market. Mix a spoonful of yeast, two poonfuls sugar with «sufficient quantity of lukewarm water in a bottle. Fix a colourless, transparent balloon on the mouth of that bottle. Find out how to use the solution prepared in the above experiment, to make bread. Follow the recipe and make the bread. Find out and note down the reasons why the dough rises and makes the bread spongy.

Take a long rubber band and cut it at one point . At one of its ends tie a clean washed stone or a 50g weight as shown in figure Now hold the other end of the rubber band and make a mark there . Keep the stone hanging in air and measure the length of the rubber band from the stone to the mark made earlier . now take water in a pot and hold the rubber band at such a height that the stone sinks in it . again measure the length of the rubber band up to the mark . : What could be the reason for a shorter length of the rubber band in water ? :

Pratik takes 8 hours to travel 36 km downstream and return to same spot. The speed of boat in still water is 12km/hr. Find the speed of the water current.

Take a plastic bottle . Pierce it with a thick needle at the points 1,2,3 as shown in thefigure . Fill water in the bottle upto full height . As shown in the figure , water jets will be seen emerging and projecting out . The water jet emerging from the hole at the top will fall closest to the bottle . the jet from the lowest hole falls farthest from the bottle . also , jets coming out from the two holes at the same level fall atthe same distance from the bottle . what is understood from this ?:

Take a long rubber band and cut it at one point . At one of its ends tie a clean washed stone or a 50g weight as shown in figure Now hold the other end of the rubber band and make a mark there . Keep the stone hanging in air and measure the length of the rubber band from the stone to the mark made earlier . now take water in a pot and hold the rubber band at such a height that the stone sinks in it . again measure the length of the rubber band up to the mark . : What is observed ?:

A balloon has 5 g of air. A small hole is pierced into it. The air escapes at a uniform rate with a velocity of 4 cm/s. If the balloon shrinks completely in 2.5 s, then the average force acting on the balloon is

Two persons of masses 55 kg and 65 kg respectively are at the opposite ends of a boat. The length of the boat is 3.0 m and weights 100 kg . The 55 kg man walks up to the 65 kg man and sits with him. If the boat is in still water the centre of mass of the system shifts by.

Water is flowing in a stream with velocity 5 km/hr in an easterly direction relative to the shore. Speed of a boat is relative to still water is 20 km/hr. If the boat enters the stream heading North, with what velocity will the boat actually travel?