Question

(d) Due to liquid pressure swer the following questions. State Pascal's law. Write any two applications of Pascal's law What is hydraulic lift? How does hydraulic press work? Write any two uses of hydraulic press We experience nose bleeding while trekking to high altitude why? What is up thrust? What is the relation between density of liquid and it's up thrust? The pieces of ice float on water. Give reason. Why is it easier to swim in sea than in a pond or river? Study the figure given below and answer the following questions: ​

Answer 1

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Answer 2

Here is the answer to your individual questions:

1. State Pascal's law :

• Pascal's Law states that in a fluid at rest in a closed container, a pressure change is transmitted without loss to every portion of the fluid.

    2. Write any two applications of Pascal's law :

         i. Hydraulic braking system present in the automobiles.

        ii. Hydraulic Lift

   3. What is hydraulic lift?:

• It is a device used for moving objects by applying pressure on a fluid. which in turn, forces the piston (on which object is kept) to move upwards  As an application of Pascal's Law, it makes use of the formula

                           pressure = $\frac{force}{area}$

        to move a heavy object by applying a small force.

   4.   How does hydraulic press work? Write any two uses of hydraulic  press:

• A hydraulic press consists of 2 cylinders connected to each other. The larger cylinder is called ram and smaller is called plunger. Both are filled with incompressible fluids.

• The hydraulic press works by applying a small amount of force onto the Plunger which presses the fluid below. This pressure is then distributed evenly which in turn raises the Ram. The pressure between the Plunger and the Ram then works to crush the item placed between them.

• Hydraulic press is used for pressing metallic objects into a sheet of metal and thinning glass.

  5. We experience nose bleeding while trekking to high altitude.Why?

• We experience nose bleed while trekking to high altitudes because at high altitudes the atmospheric pressure gets reduced to less than our blood pressure.
• Therefore, blood starts moving from a place of high pressure to low pressure, i.e, from inside the body to outside, hence we experience nose bleeds in high altitude.

  6. What is up thrust?

• Upthrust is an upward force exerted by a fluid that opposes the weight of an immersed object.It is the force that pushes an object up.

7. What is the relation between density of liquid and it's up thrust?

• According to Archimede's Principle, upthrust or buoyant force is equal to the weight of fluid displaced by the object.

                      B = W

Where W= weight of fluid displaced, which can be written as

           W = (ρV)g                               (mass = density × volume)

           ρ = density of liquid

           V is volume displaced

          Weight = mass × acceleration due to gravity

                              ⇒ B = ρVg

Therefore, upthrust is directly proportional to the density of the object it is acting on.

  8. The pieces of ice float on water. Give reason.

• Ice floats on water because it is less dense than water.

• Water forms hydrogen bonds when it freezes to ice. It forms a cage-like structure allowing the molecules to be spaced farther apart, and decreases the overall density and making it float in water.

  9. Why is it easier to swim in sea than in a pond or river?

• Due to high salt levels in sea water its density is higher as compared to river water.

• So as the density increases the buoyant force also increases. The swimmer feels a stronger upthrust which keeps him afloat more easily. So, it is easier to swim in sea rather than in pond or river.