Q1. Force is a_______________ quantity.

Ans: Vector

Q2. SI unit of force is _______________.

Ans: Newton (N)

Q3. 1 Newton = Force required to move _______________ kg mass with acceleration of _________ m/s².

Ans: 1 kg, 1 m/s²

Q4. A push or pull on an object is called _________.

Ans: Force

Q5. Pressure is defined as _________.

Ans: Force per unit area

Q6. SI unit of pressure is _________.

Ans: Pascal (Pa)

Q7. 1 Pascal = Force of _________ applied on _________ area.

Ans: 1 N, 1 m²

Q8. Atmospheric pressure at sea level = _________.

Ans: 1.01 × 10⁵ Pa

Q9. Pressure exerted by liquid depends on _________.

Ans: Depth, density, and acceleration due to gravity

Q10. A force can change the _________ of an object.

Ans: Shape, speed, and direction

Q11. True or False: Friction is a type of contact force.

Ans: True

Q12. True or False: Magnetic force is a non-contact force.

Ans: True

Q13. Contact force includes _________ and _________.

Ans: Friction, muscular force

Q14. Non-contact force includes _________, _________, and _________.

Ans: Gravitational, magnetic, electrostatic

Q15. The force exerted by air is called _________.

Ans: Air pressure

Q16. Pressure is inversely proportional to _________.

Ans: Area

Q17. The SI unit of pressure is named after _________.

Ans: Blaise Pascal

Q18. Liquids exert pressure in _________ directions.

Ans: All

Q19. The force exerted by Earth on an object is called _________.

Ans: Gravitational force (weight)

Q20. Weight = Mass × _________.

Ans: Gravitational acceleration (g)

Q21. A nail penetrates wood easily because _________.

Ans: Small area → high pressure

Q22. A camel can walk easily on sand due to _________.

Ans: Large feet → less pressure

Q23. True or False: Pressure in fluids increases with height.

Ans: False (increases with depth)

Q24. The unit of thrust is _________.

Ans: Newton

Q25. Pressure cooker cooks food faster because _________.

Ans: High pressure raises boiling point

Q26. The upward force exerted by liquids is called _________.

Ans: Buoyant force

Q27. The instrument used to measure atmospheric pressure is _________.

Ans: Barometer

Q28. Unit of thrust and force are same. (True/False)

Ans: True

Q29. Pressure depends only on _________ and _________.

Ans: Force, area

Q30. SI unit of thrust is _________.

Ans: Newton

 Short & Long Answers

Q31. Define force.

Ans: A push or pull that can change the state of motion or shape of an object.

Q32. Differentiate between contact and non-contact forces.

Ans: Contact forces act with physical touch (friction, muscular), non-contact act without touch (gravity, magnetism).

Q33. State Newton’s first law of motion in simple terms.

Ans: An object remains at rest or in uniform motion unless acted upon by an external force.

Q34. What are the effects of force?

Ans: Force can change speed, direction, and shape of objects.

Q35. Define pressure.

Ans: The force acting per unit area on a surface.

Q36. Why are knives made with sharp edges?

Ans: Small area increases pressure, making cutting easier.

Q37. Why do tractors have wide tyres?

Ans: Wide tyres reduce pressure, preventing sinking into soil.

Q38. What is thrust?

Ans: The total force acting perpendicular on a surface.

Q39. Why do deep-sea divers wear special suits?

Ans: To withstand high water pressure.

Q40. Why is it easier to cut vegetables with a sharp knife?

Ans: Smaller area → higher pressure for same force.

Q41. Why does a dam have a thicker wall at the bottom?

Ans: Water pressure increases with depth.

Q42. Give an example of muscular force.

Ans: Lifting a book.

Q43. Why do astronauts feel weightless in space?

Ans: Because they are in free fall under gravity.

Q44. What is atmospheric pressure?

Ans: The pressure exerted by air in the Earth’s atmosphere.

Q45. State Pascal’s law.

Ans: Pressure applied on a liquid in a closed vessel is transmitted equally in all directions.

Q46. Why does pressure increase with depth in liquids?

Ans: Because weight of liquid above increases.

Q47. What is buoyancy?

Ans: The upward force exerted by fluids on a body immersed in it.

Q48. Give two examples of non-contact forces.

Ans: Gravitational and magnetic force.

Q49. Why does a balloon burst when pressed hard?

Ans: Large force on small area → high pressure.

Q50. Why do camels have broad feet?

Ans: To reduce pressure on sand.

Q51. Explain why dams are broader at the base.

Ans: To resist greater pressure at depth.

Q52. Why do we feel uneasy climbing mountains?

Ans: Reduced air pressure, less oxygen.

Q53. Define gravitational force.

Ans: Force by which Earth attracts objects towards its center.

Q54. Why do we not get crushed under atmospheric pressure?

Ans: Pressure inside our body balances it.

Q55. Explain why a person using a pointed heel exerts more pressure.

Ans: Smaller area → more pressure.

Q56. Why does pressure cooker lid whistle?

Ans: High steam pressure escapes suddenly.

Q57. Why does a liquid exert pressure sideways?

Ans: Liquids transmit pressure in all directions.

Q58. Differentiate between mass and weight.

Ans: Mass is quantity of matter (kg), weight is force of gravity (N).

Q59. Why are vehicles fitted with broad tyres?

Ans: To reduce pressure on road.

Q60. What is hydraulic press based on?

Ans: Pascal’s law.

Q61. Why does an object sink or float?

Ans: Depends on relation between object’s weight and buoyant force.

Q62. Why is it difficult to walk on sand with high heels?

Ans: Small area → high pressure → heels sink.

Q63. What is the relation between thrust and pressure?

Ans: Pressure = Thrust / Area

Q64. Why is atmospheric pressure important for life?

Ans: Helps in breathing, boiling of liquids, weather balance.

Q65. Why do mountain climbers carry oxygen cylinders?

Ans: Because air pressure and oxygen level decrease at height.

Q66. Why does suction work?

Ans: Atmospheric pressure pushes liquid into vacuum.

Q67. What causes tides?

Ans: Gravitational pull of moon and sun.

Q68. Why are hydraulic brakes used in vehicles?

Ans: Pressure transmission through liquid multiplies force.

Q69. Why do astronauts wear space suits?

Ans: To protect from very low pressure in space.

Q70. Give an example where pressure is useful.

Ans: Syringes, hydraulic lifts.

Q71. A force of 200 N acts on an area of 2 m². Find pressure.

Ans: P = F/A = 200/2 = 100 Pa

Q72. A thrust of 500 N acts on area 0.5 m². Find pressure.

Ans: P = 500/0.5 = 1000 Pa

Q73. A man of mass 60 kg stands on ground. Area of his feet = 0.02 m². Pressure exerted? (g=10 m/s²)

Ans: F = mg = 600 N, P=600/0.02=30,000 Pa

Q74. A block of weight 100 N placed on ground with area 0.25 m². Find pressure.

Ans: P=100/0.25=400 Pa

Q75. A box exerts pressure of 500 Pa on floor. If area of contact=0.2 m², find force.

Ans: F = P×A = 500×0.2=100 N

Q76. An elephant of mass 4000 kg stands on four feet, each area=0.1 m². Find pressure (g=10).

Ans: F=4000×10=40000 N, A=0.4, P=40000/0.4=100,000 Pa

Q77. A girl of mass 50 kg wears shoes with heel area 0.001 m². Find pressure.

Ans: F=500 N, P=500/0.001=500,000 Pa

Q78. A boy exerts force of 200 N on area 0.05 m². Find pressure.

Ans: 200/0.05=4000 Pa

Q79. A thrust of 1000 N acts on area 0.25 m². Find pressure.

Ans: 1000/0.25=4000 Pa

Q80. A block exerts pressure of 2000 Pa on floor. Area=0.5 m². Find force.

Ans: 2000×0.5=1000 N

Q81. A liquid of density 1000 kg/m³ is at depth 10 m. Find pressure (g=10).

Ans: P=ρgh=1000×10×10=100,000 Pa

Q82. At depth 20 m in water, pressure = ? (ρ=1000, g=10).

Ans: P=1000×10×20=200,000 Pa

Q83. At what depth in water pressure=50,000 Pa? (ρ=1000, g=10)

Ans: h=P/ρg=50,000/10000=5 m

Q84. A tank filled with oil of density 800 kg/m³. Depth=5 m. Pressure? (g=10)

Ans: P=ρgh=800×10×5=40,000 Pa

Q85. A swimmer 15 m below surface feels pressure? (ρ=1000, g=10)

Ans: 1000×10×15=150,000 Pa

Q86. A thrust of 200 N acts on 0.01 m². Pressure?

Ans: 200/0.01=20,000 Pa

Q87. A box mass 10 kg, area of base 0.05 m². Find pressure. (g=10)

Ans: F=100 N, P=100/0.05=2000 Pa

Q88. An object mass 2 kg, area=0.01 m². Pressure? (g=10)

Ans: 20/0.01=2000 Pa

Q89. Find force exerted when pressure=2500 Pa, area=0.2 m².

Ans: 2500×0.2=500 N

Q90. A hydraulic press multiplies force 20 times. If input=100 N, output=?

Ans: 100×20=2000 N

Q91. Pressure at 30 m in water? (ρ=1000, g=10)

Ans: 1000×10×30=300,000 Pa

Q92. A force of 150 N applied on 0.03 m². Pressure?

Ans: 150/0.03=5000 Pa

Q93. Pressure exerted by 500 N force on 0.25 m²?

Ans: 500/0.25=2000 Pa

Q94. A person of weight 700 N stands on shoes, total area=0.025 m². Pressure?

Ans: 700/0.025=28,000 Pa

Q95. A water column exerts pressure 60,000 Pa. Height=? (ρ=1000, g=10)

Ans: h=60000/10000=6 m

Q96. Pressure exerted by 50 N force on 10 cm²? (1 cm²=0.0001 m²)

Ans: A=0.001 m², P=50/0.001=50,000 Pa

Q97. A hydraulic lift multiplies force 100 times. If output force=5000 N, input force=?

Ans: 5000/100=50 N

Q98. A weight of 20 N acts on 0.02 m². Find pressure.

Ans: 20/0.02=1000 Pa

Q99. A book of mass 2 kg has base area 0.04 m². Pressure? (g=10)

Ans: F=20 N, P=20/0.04=500 Pa

Q100. A man of 70 kg stands on one foot, area=0.02 m². Find pressure. (g=10)

Ans: F=700 N, P=700/0.02=35,000 Pa