Why is the weight of an object on the moon 1/6th its weight on the earth?
WE = the object on the surface of the Earth
Let, MM = mass of the moon
RM = radius of the moon
WM = the object on the surface of the moon
Convert into mole.
(a) 12 g of oxygen gas
(b) 20 g of water
(c) 22 g of carbon dioxide.
Illustrate the law of conservation of energy by discussing the energy changes which occur when we draw a pendulum bob to one side and allow it to oscillate. Why does the bob eventually come to rest? What happens to its energy eventually? Is it a violation of the law of conservation of energy?
Why is the atmosphere essential for life?
You find your mass to be 42 kg on a weighing machine. Is your mass more or less than 42 kg?
What happens to the force between two objects, if
(i) the mass of one object is doubled?
(ii) the distance between the objects is doubled and tripled?
(iii) the masses of both objects are doubled?
Why are we normally advised to take bland and nourishing food when we are sick?
What are the immunisation programmes available at the nearest health centre in your locality? Which of these diseases are the major health problems in your area?
In which of the following case do you think the long-term effects on your health are likely to be most unpleasant?
• if you get jaundice,
• if you get lice,
• if you get acne.
Why?
A stone is released from the top of a tower of height 19.6 m. Calculate its final velocity.
List any three human activities that you think would lead to air pollution.
You have a bag of cotton and an iron bar, each indicating a mass of 100 kg when measured on a weighing machine. In reality, one is heavier than other. Can you say which one is heavier and why?
A pair of bullocks exerts a force of 140 N on a plough. The field being ploughed is 15 m long. How much work is done in ploughing the length of the field?
How does the force of gravitation between two objects change when the distance between them is reduced to half ?
In which of the following case do you think the long-term effects on your health are likely to be most unpleasant?
• if you get jaundice,
• if you get lice,
• if you get acne.
Why?
How would you choose between two characteristics to be used for developing a hierarchy in classification?
List any three human activities that you think would lead to air pollution.
Why are manure and fertilizers used in fields?
Convert into mole.
(a) 12 g of oxygen gas
(b) 20 g of water
(c) 22 g of carbon dioxide.
Write down the formulae of
(i) sodium oxide
(ii) aluminium chloride
(iii) sodium suphide
(iv) magnesium hydroxide
On what bases are plants and animals put into different categories?