Listen NCERT Audio Books to boost your productivity and retention power by 2X.
State whether the following statements are true or false:
(a) A falling stone also attracts the earth.
(b) The force of gravitation between two objects depends on the nature of medium between them.
(c) The value of G on the moon is about one-sixth of the value of G on the earth.
(d) The acceleration due to gravity acting on a freely falling body is directly proportional to the mass of the body.
(e) The weight of an object on the earth is about one-sixth of its weight on the moon.
Fill in the following blanks with suitable words:
(a) The acceleration due to gravity on the moon is about ……..of that one the earth.
(b) In order that the force of gravitational between two bodies may become noticeable and cause motion, one of the bodies must have an extremely large ………..
(c) The weight of an object on the earth is about …………..of its weight on the moon.
(d) The weight of an object on the moon is about ………….of its weight on the earth.
(e) The value of g on the earth is about ………of that on the moon.
(f) If the weight of a body is 6 N on the moon, it will be about …………… on the earth.
An apple of mass 100 g. falls from a tree because of gravitational attraction between the earth and the apple. If the magnitude of force exerted by the earth on the apple be F1 and the magnitude of force exerted by the apple on the earth be F2 then:
A. F1 is very much greater than F2
B. F2 is very much greater then F1
C. F1 is only a little greater than F2
D. F1 and F2 are exactly equal
The values of g at six distances A, B, C, D, E and F from the surface of the earth are found to be 3.08 m/s2, 9.23 m/s2, 0.57 m/s2, 7.34 m/s2, 0.30 m/s2 and 1.49 m/s2, respectively.
(a) Arrange these values of g according to the increasing distances from the surface of the earth (keeping the value of g nearest to the surface of the earth first)
(b) If the value of distance F be 10000 km from the surface of the earth, state whether this distance is deep inside the earth or high up in the sky. Give reason for your answer.
Fill in the blanks with suitable words:
(a) Force acting on a unit area is called ………..
(b) It is the ……… force which makes objects appear lighter in water.
(c) A heavy ship floats in water because its ………. Density is less than that of water.
(d) In fluids (liquids and gases), pressure acts in ……..directions, and pressure …………..as the depth increases.
(e) In order to sink in a fluid, the density of an object must be ………. Than the …….. of the fluid.
(f) Snow shoes work by spreading out a person’s ………….. over a much bigger ……..
(g) If the area of a snow shoe is five times ……… than the area of an ordinary shoe, them the pressure of a snow shoe on the snow is five times ………………
An elephant weighing 40,000 N stands on one foot of area 000 cm2 whereas a girl weighing 400 N is standing on one ‘stiletto’ heel of area 1 cm2. (Pictures)
(a) Which of the two, elephant or girl, exerts a larger force on the ground and by how much?
(b) What pressure is exerted on the ground by the elephant standing on one foot?
(c) What pressure is exerted on the ground by the girl standing on one heel?
(d) Which of the two exerts larger pressure on the ground: elephant or girl?
(e) What is the ratio of pressure exerted by the girl to the pressure exerted by the elephant?
A rectangular wooden block has length, breadth and height of 50 cm, 25 cm and 10 cm, respectively. This wooden block is kept on ground in three different ways, turn by turn. Which of the following is the correct statement about the pressure exerted by this block on the ground?
A. The maximum pressure is exerted when the length and breadth from the base
B. The maximum pressure is exerted when length and height from the base
C. The maximum pressure is exerted when breadth and height form the base
D. The minimum pressure is exerted when length and height form the base
An object is put in three liquids having different densities, one by one. The object floats with and parts of its volume outside the surface of liquids of densities d1, d2, and d3 respectively. Which of the following is the correct order of the densities of the three liquids?
A. d1> d2> d3 B. d2> d3> d1
C. d1< d2< d3 D. d3> d2> d1
Consider the following information in respect of four objects A, B, C and D:
Which object would float on water?