State Archimedes' principle? Write two applications of Archimedes' principle.

If a fresh egg is put into a beaker filled with water, it sinks. On dissolving a lot of salt in the water, the egg begins to rise and floats. Why?

The earth is not a perfect sphere. As the radius of the radius of the earth increases from the poles to the equator, the value of g becomes greater at the poles than at the equator. As one goes above the earth's surface, the value of g decreases. If one goes deep inside the earth, then also the value of g decreases. In fact, the value of g becomes zero at the centre of the earth. Moreover, due to the rotation of the earth, the weight of a body is maximum at the poles and minimum at the equator.
(i) Name the factors on which the value of 'g' depends.
(ii) What is the effect of altitude on acceleration due to gravity?
(iii) What is the effect of rotation of the earth on the acceleration due to gravity?

A cubical tub of side 2 m is full of water. Calculate the total thrust and pressure at the bottom of tank due to water. (Take, density of water = 1000 kg m^-3 and g = 10 ms^-2)

Two different bodies are completely immersed in water and undergo the same loss in weight. Is it necessary that their weights in air should also be the same? Justify your answer.

If the distance between two masses beincreased by a factor of 6, by what factor would the mass of one of them have to be altered to maintain the same gravitational force? Would this be an increase or decrease in mass?

Two solid objects of masses 1 kg and 2 kg are dropped from a helicopter at the same time. Which one will reach the ground earlier? Justify your answer with suitable reason

Calculate the acceleration due to gravity on the surface of satellite having mass 7.4 x 10²² kg and radius 1.74 x 10⁶ cm. (Take,G = 6.7 X 10^-11 N-m/kg²)

Prove that, if a body is thrown vertically upwards, then the time of ascent is equal to the time of descent.

A ball is thrown with some speed u mls. Show that under the free fall, it will fall on the ground with same speed.

A ball is dropped from the edge of a roof. It takes 0.1 s to cross a window of height 2.0 m. Find the height of the roof above the top of the window.

A particle weighs 120 N on the surface of the earth. At what height above the earth's surface will its weight be 30 N? Radius of the earth = 6400 km.

(i) State the SI units of thrust and pressure.
(ii) In which situation, we exert more pressure on ground when we stand on one foot or on the both feet? Justify your answer.

Mohit throws a ball horizontally while Shobhit throws a ball vertically downwards from a tower. Both of them do so in an attempt to see who hits the stone on ground first. After that, they try to reason their findings.
Read the above passage and answer the following questions:
(i) Which ball reaches the ground first?
(ii) What are the values shown by Mohit and Shobhit?
(iii) What is the relation of g with G?

Shruti and Kriti were performing the experiment to find the pressure exerted by a cuboid kept on sand with its different faces. Shruti shared her thoughts with Kriti and told her that, since the teacher had explained about pressure and area, therefore she could guess the results.
(i) How can you relate pressure applied by an object with its area?
(ii) What would be the observation of Shruti and Kriti?
(iii) Which qualities about Shruti do you observe from here?