On the basis of the issues raised in this chapter, what changes would you incorporate in your lifestyle in a move towards a sustainable use of our resources ?

What changes would you suggest in your home in order to be environment-friendly?

Why do you think that there should be equitable distribution of resources? What forces would be working against an equitable distribution of our resources ?

To check the pH of tap water and compare it with pH of the water in the local water body. Apparatus : Test tubes or beaker Materials : Universal pH indicator / litmus paper Procedure : implies Take water sample from tap of your home in a test tube. implies Add few drops of the universal indicator into the test tube containing tap water. implies Observe the water sample in the test tube for colour change. implies Test pH using a litmus paper, in the water sample placed in a beaker. implies Dip the litmus paper into the water in the local water body. implies Observe colour changes of the litmus paper. Observation : implies Test tube containing tap water, turns yellow colour with addition of pH indicator. implies Litmus paper does not show colour change with tap water. implies Water sample collected from pond shows red colour with pH indicator. Litmus paper turns red as it is dipped in water of local water body. Conclusion : The uncontaminated tap water is neutral while water of local water body is acidic. Can you say whether the water is polluted or not on the basis of your observations?

To find out the names of organisations involved in spreading awareness about the conservation of natural resources. NGO (Non Government Organisations) such us SEACOLOGY and Mera Desh Foundation spread awareness about the environment and promote activities that lead to conservation of natural resources. Some other organisations that work for the conservation of the environment. CSE - The Centre for Science and Environment, TER- The Energy and Resources Institute, WTI - Wildlife Trust of India. How you can contribute towards the conservation of our environment and natural resources.

Imagine that you are sitting in a chamber with you back to one wall. An electron beam , moving horizontlly from back wall towards the front wall , is deflected by a stong magnetic field to your right side. What is the direction of magnetic field ?

One hard and stormy night you find yourself lost in the forest when you come upon a small hut. Entering it you see a crooked old woman in the corner hunched over a crystal ball. You are about to make a hasty exit when you hear the howl of wolves outside. Taking another look at the gyspy you decide to take your chances with the wolves, but the door is jammed shut. Resigned to a bad situation you approach her slowly, wondering just what is the focal length of that nifty crystal ball. The old lady moves the crystal ball closer to her wrinkled old face. At some point you can no longer get an image of her . At what object distance will there be no change of the gypsy formed?

By the term velocity of rain, we mean velocity with which raindrops fall relative to the ground. In absence of wind, raindrops fall vertically and in presence of wind raindrops fall obliqucly. Moreover raindrops acquire a constant terminal velocity due air resistance very quickly as they fall toward the carth. A moving man relative to himself observes an altered velocity of raindrops. Which is known as velocity of rain relative to the man. It is given by the following equation. vec(v)_(rm)=vec(v)_(r)-vec(v)_(m) A standstill man relative to himself observes rain falling with velocity, which is equal to velocity of the raindrops relative to the ground. To protect himself a man should his umbrella against velocity of raindrops relative to himself as shown in the following figure. When you are standstill in rain, you have to hold umbrella vertically to protect yourself. (a) When you walk with velocity 90 cm/s, you have to hold your umbrella at 53^(@) above the horizontal. What is velocity of the raindrops relative to the ground and relative to you ? (b) If you walk with speed 160 cm/s, how should you hold your umbrella ?

Guess my number : Your frient chooses an integer between 0 and 100. You have to find out that number by asking questions, but your friend can answer only in 'yes' or 'no'. What strategy would you use?

(a) When a molecule (or an elastic ball) hits a ( massive) wall, it rebounds with the same speed. When a ball hits a massive bat held firmly, the same thing happens. However, when the bat is moving towards the ball, the ball rebounds with a different speed. Does the ball move faster or slower? (b) When gas in a cylinder is compressed by pushing in a piston, its temperature rises. Guess at an explanation of this in terms of kinetic theory using (a) above. (c) What happens when a compressed gas pushes a piston out and expands. What would you observe ? (d) Sachin Tendulkar used a heavy cricket bat while playing. Did it help him in anyway ?