# 2 Marks Question

1. What happens if an egg is kept in two beakers containing pure water and saturated salt solution? Why?
2. If an egg is immersed in pure water it sinks while in saturated salt solution it floats. The density of the egg is more than the density of pure water. So, the egg cannot displace water equal to its weight and it sinks. But the density of the egg is less than the density of salt solution so the egg can displace salt solution water equal to its own weight and it floats.
3. Write any two differences between Archimedes’ principle and the law of floatation.
4. Any two differences between Archimedes’ principle and law of floatation is shown below in table:
Archimedes’ Principle Law of floatation
According to Archimedes’ Principle,
weight of liquid displaced = upthrust
According to law of flotation,
weight of liquid displaced = weight of floating body
It explains about floating as well as sinking objects. It explains about only the floating body.
5. An object weights 20 N in air and 16 N in liquid then answer the following questions.
1. What is the upthrust of the liquid on the object?
We know,
upthrust = weight of object in air - weight of object in water
or, upthrust = 20N – 16N
∴ Upthrust = 4N ------- (i)
2. What is the weight of the displaced liquid? Write with reason.
According to Archimedes’ principle,
weight of the displaced liquid = upthrust = 4N (form equation i)
∴ Weight of the displaced liquid = 4N.
6. Hydraulic press is called an instrument for multiplication of force, why?
7. According to Pascal's law,
Pressure on the small piston = Pressure on the large piston
or, P1 = P2
or, $\frac{F_1}{A_1}$ = $\frac{F_2}{A_2}$
or, F2 = F1 × $\frac{A_2}{A_1}$ (A2 > A1)

If a certain force is applied in smaller piston of hydraulic press it gives a downward pressure. According to the pascal’s law, this pressure is transmitted in all direction. As a result the load is raised in the larger piston. Greater load can be raised by applying a small force. So, the hydraulic press can act as a force multiplier.

8. What happens to balloon filled with air, when it goes very high altitude from surface of earth? Why?
9. When balloon filled with air goes to high altitude, it bursts because when it goes to high altitude the atmospheric pressure goes on decreasing but the pressure inside balloon remains same. This means internal pressure is more than external atmospheric pressure.
10. A ship sinks more when extra load is added to it. Why?
11. A ship sinks more to displace extra volume of water equivalent to added load. Such that if the weight of extra (displaced) water is equal to added load, the ship floats otherwise sinks in the water.
12. Write any two importance of atmospheric pressure.
13. Any two importance of atmospheric pressure are listed below:
1. To fill inks in a pen.
2. To fill up air using air pumps.
14. In the given figure, weight of stone inside water is 9N and water displaced by stone is 2N then: 1. What is the actual weight of stone?
Actual weight = weight of stone inside water + water displaced by stone
= 9 + 2
= 11N.
2. Which principle is this experiment based on?
This experiment is based on Archimedes principle.
15. Write two differences between force and pressure.
16. Differences between force and pressure is shown below in table:
Force Pressure
An external agent that changes the state of any object is force. Force per unit area is pressure.
Its SI unit is Newton (N). Its SI unit is Pascal (Pa).
17. What is the relation between the density of liquid and the upthrust exerted by the liquid?
18. Upthrust experienced by a body depends upon the volume of its immersed part and the density of the liquid. The larger the volume of immersed body grater is the upthrust. Hence, upthrust is directly proportional to the density of the liquid.
19. An iron nail sinks in water but floats in mercury, why?
20. An iron nail sinks in water because the density of the iron nail is greater than that of water. So, it cannot displace water equal to its weight and sinks. While it floats in mercury because the density of iron nail is less than that of mercury. So, it can displace mercury equal to its weight and floats.
21. Write a condition in which the object having more density than liquid floats on the liquid.
22. If the object having greater density than liquid is given suitable shape so that it can displace the liquid equal to its own weight, it can float on the liquid.
23. Ship can carry more load in sea water than in river water, why?
24. The density of seawater is more than that of river water because seawater contains a large amount of salt, thus seawater provides more upthrust as compared to river water. So, ship can carry more load in seawater.
25. Mention the relation between the density of the liquid and its upthrust. It is easier to swim in seawater than in the river, why?
26. Upthrust experienced by a body depends upon the volume of its immersed part and the density of the liquid. The larger the volume of immersed body grater is the upthrust. Hence, upthrust is directly proportional to the density of the liquid.
The density of seawater is more than that of river water because seawater contains a large amount of salt, thus seawater provides more upthrust as compared to the river water which makes it easier to swim in seawater.
27. Why is it easier to pull a bucket of water from the well until it is inside the water but difficult out of water?
28. In water, there is more upthrust than that of air which gives more upward acting force to the bucket. So, it makes it easier to pull a bucket in water than in the air.
29. What difference is observed if an egg is immersed in pure water and in concentrated salt solution?
30. If an egg is immersed in pure water it sinks while in concentrated salt solution it floats. The density of egg is more than density of pure water. So, the egg cannot displace water equal to its weight and it sinks. But the density of egg is less than density of salt solution so egg can displace salt solution water equal to its own weight and it floats.
31. It is easier to lift a heavy stone inside the water than air, why?
32. It is easier to lift a heavy stone inside the water than air because in water there is more upthrust than that of air which give more upward acting force to the stone.
33. What is the difference between an empty ship and loaded ship moving on the sea water?
34. The difference between an empty ship and loaded ship moving on the sea water is that empty ship sinks less than the loaded ship. Similarly, empty ship displace less amount of liquid with respect to the liquid displaced by the load ship.
35. Studs are made on the sole of football player's boot, why?
36. Since the pressure exerted by a body is inversely proportional to the surface area for the same applied force.
i.e. P ∝ 1/A

The surface of the studs of the sole of a football player's shoe is less than that of a flat sole. Consequently, the studs sole exerts more pressure on the ground. It makes it easy for the player to run and jump as well as protects from slipping the player. That's why studs are made on the sole of a football player's boot.

37. The pressure applied in an enclosed liquid is transmitted equally in all directions perpendicular to the surface. Which law is explained by this statement? Name the instrument which works on the basics of this law.
38. Pascal's law is explained by this statement. The name of the instrument based on pascal law are: hydraulic press, hydraulic brakes, jacks, hydraulic lift etc.
39. An iron pin sinks in water but a ship made up of iron floats on it, why?
40. The density of nail of iron is greater than that of water. Nail cannot displace water equal to its weight. So, nail sinks in water. The ship is so shaped that it is capable of displacing water equal to its weight. So, it can float on water.
41. We experience nose bleeding while trekking to high altitude, why?
42. When we go to a higher altitudes, the atmospheric pressure goes on decreasing but our blood pressure remains the same. This means internal blood pressure is more than external atmospheric pressure. Thus, the blood vessel present inside the nose feels high pressure and rupture.
43. What is atmospheric pressure? Name the instrument that measures atmospheric pressure.
44. The pressure exerted by the weight of air on the surface of the earth is called atmospheric pressure. The instrument that measures atmospheric pressure is barometer.