Pressure and Pascal's Law - UNSOLVED PRACTICE SET
Chapter: Mechanical Properties of Fluids | Topic: Pressure and Pascals Law
PRESSURE AND PASCAL'S LAW - UNSOLVED PRACTICE SET
Topic: Pressure and Pascals Law
Multiple Choice Questions
Q1. Pressure at a point in a fluid is defined as:
- Force per unit volume
- Force per unit area acting normal to the surface
- Force per unit length
- Total force acting on the fluid
Q2. According to Pascal's law, pressure applied to an enclosed fluid:
- Decreases as it moves away from the point of application
- Is transmitted undiminished to every portion of the fluid and walls of the container
- Acts only in the downward direction
- Is absorbed by the fluid
Q3. The SI unit of pressure is:
- Newton
- Pascal
- Joule
- Watt
Q4. In a hydraulic lift, a small force applied on a small piston can lift a heavy load on a large piston because:
- The pressure is the same throughout the fluid
- The fluid is incompressible
- Both (a) and (b)
- The fluid is compressible
Q5. Pressure is a:
- Vector quantity
- Scalar quantity
- Tensor quantity
- Dimensionless quantity
Q6. In a hydraulic brake system, the force applied by the driver's foot is:
- Equal to the force applied on the brake shoes
- Much smaller than the force applied on the brake shoes
- Much larger than the force applied on the brake shoes
- Independent of the force applied on the brake shoes
Short Answer Questions
Q7. Define pressure. Why is it considered a scalar quantity even though force is a vector?
Q8. State Pascal's law. Explain how it is used in a hydraulic press.
Q9. A force of 100 N is applied on a piston of area 10 cm² in a hydraulic machine. The area of the other piston is 500 cm². Calculate the force exerted on the second piston.
Q10. In your school, the physics lab has a hydraulic jack used to lift heavy equipment. Explain why a small girl can operate it to lift a heavy table, using Pascal's law.
Q11. Why are liquids used in hydraulic systems instead of gases? Explain the importance of incompressibility.
Q12. A U-tube contains water and mercury. The mercury column stands 10 cm higher in one limb than the other. Calculate the pressure difference between the two limbs. (Density of mercury = 13.6 g/cm³, g = 9.8 m/s²)
Long Answer Questions
Q13. State and explain Pascal's law with a diagram. Derive the principle of multiplication of force in a hydraulic system. Discuss three practical applications of Pascal's law with explanations.
Q14. A hydraulic lift is used to raise a car of mass 1500 kg. The diameter of the large piston is 30 cm and that of the small piston is 2 cm.
(a) Calculate the area of each piston.
(b) Calculate the force required on the small piston to lift the car.
(c) If the small piston is pushed down by 60 cm, how much does the car rise?
(d) Calculate the mechanical advantage of this system.
(e) Discuss the energy conservation in this process.
Q15. Analyse the following situations using Pascal's law:
(i) A dentist's chair
(ii) A car's hydraulic brake system
(iii) A hydraulic press in a factory
For each case, explain:
(a) How Pascal's law is applied
(b) The advantage gained
(c) Any limitations or safety considerations
Application-Based Problems
Q16. In a school science project, students build a model hydraulic lift using two syringes connected by a tube filled with water. The small syringe has a piston diameter of 1 cm and the large syringe has a piston diameter of 3 cm.
(a) Calculate the area of each piston.
(b) If a 500 g mass is placed on the small piston, what mass can be lifted on the large piston?
(c) If the small piston is pushed down by 9 cm, how much does the large piston rise?
(d) Verify that the work done on both pistons is the same (neglecting friction).
(e) Discuss two practical difficulties in making this model work perfectly.
Q17. A hydraulic press has pistons of diameters 5 cm and 50 cm. It is used to compress a metal block.
(a) Calculate the force exerted on the metal block when a force of 200 N is applied on the small piston.
(b) If the small piston moves through 20 cm, calculate the distance moved by the large piston.
(c) Calculate the work done by each piston.
(d) If the efficiency of the press is 80%, calculate the actual force on the metal block.
(e) Explain why the efficiency is not 100%.
Q18. A U-tube manometer containing mercury is connected to a gas cylinder. The mercury level in the limb connected to the gas is 15 cm lower than in the open limb.
(a) Calculate the gauge pressure of the gas in Pa.
(b) If atmospheric pressure is 1.01 × 10⁵ Pa, calculate the absolute pressure of the gas.
(c) The gas is now heated and the mercury difference becomes 20 cm. Calculate the new gauge pressure.
(d) Explain why mercury is preferred over water in manometers.
(e) Design a simple school-level experiment to demonstrate Pascal's law using a plastic bottle and holes at different heights.