A cheetah, on seeing a prey, moves towards him at a very high speed. What causes the movement of his muscles ? How does the chemistry of cellular components of muscle change during this event ?

A cheetah, on seeing a prey, moves towards him at a very high speed. What causes the movement of his muscles? How does the chemistry of cellular components of muscles change during this event?

A person moves with a velocity v towards a plane mirror. With what velocity does his image move towards him ?

A person moves with a velocity v towards a plane mirror. With what velocity does his image move towards him ?

A man from the top of a 100 m high tower sees a car moving towards the tower at an angle of depression 30°. After some time, the angle of depression becomes 60°. What is the distance travelled by the car during this time ?

When extremely small particles X derived from the anther of a flower were suspended in a liquid Y and observed through a microscope, it was found that the particles X were moving throughout the liquid Y in a very zig-zag way. It was also observed that warmer the liquid Y, faster the particles X moved on its surface. What could particles X be ? (b) What do you think liquid Y is ? (c ) What is zig-zag movement of X known as ? (d) What is causing the zig-zag movement of particles X ? (e) Name the scientist who discovered this phenomenon. (f) What does this experiment tell us about the nature of liquid Y ?

A student places a candle flame at a distance of about 60 cm from a convex lens of focal length 10 cm and focuses the umage of the flame on a screen. After that he gradually moves the flame towards the lens and each time focuses the image on the screen. (a) In which direction-toward or away from the lens, does he move the screen to focus the image ? (b) How does the size of the image change ? (c) How does the intensity of the image change as the flame moves towards the lens ? (d) Approximately for what distance between the flame and the lens, the image formed on the screen is inverted and of the same size ?

When a beam of sunlight enters a room through a window, we can see tiny particles X suspended in a gas (or rather a mixture of gases) Y which are moving rapidly in a very haphazard manner. (a) What could particles X be ? Name the gas (or mixture of gases) Y. (c ) What is the phenomenon exhibited by particles X known as ? (d) What is causing the movement of particles X ? (e) What conclusion does the existence of this phenomenon give us about the nature of matter ?

An athlletic coach told his team that muscle times speed equals power. What dimesions does he view for muscle?