ICSE Class 10 Physics: Machines — Important Questions with Answers 2026

Short Answer Questions (2-3 Marks)

• Q: What is a simple machine? State two advantages of using machines.
  Ans: A simple machine is a device that makes work easier by changing the direction, magnitude, or point of application of force. Advantages: (1) It enables us to overcome a large resistive force by applying a small effort. (2) It helps in changing the direction of the effort to a more convenient one.
• Q: Define: (i) Mechanical Advantage, (ii) Velocity Ratio, (iii) Efficiency of a machine.
  Ans: (i) Mechanical Advantage (MA) = Load/Effort = L/E. It has no unit. (ii) Velocity Ratio (VR) = Distance moved by effort / Distance moved by load = dE/dL. (iii) Efficiency η = (MA/VR) × 100% = (Work output / Work input) × 100%.
• Q: Prove that for an ideal machine, MA = VR.
  Ans: For an ideal machine (frictionless), efficiency η = 100%. Work input = Work output. E × dE = L × dL. Therefore L/E = dE/dL, i.e., MA = VR.
• Q: Why is the efficiency of a machine always less than 100%?
  Ans: In practice, friction exists between moving parts of a machine. Some input energy is wasted in overcoming friction and is converted to heat. Therefore, work output is always less than work input, making efficiency less than 100%.
• Q: For a lever of first order, the effort arm is 80 cm and load arm is 20 cm. Find the MA and VR.
  Ans: For a lever: VR = Effort arm / Load arm = 80/20 = 4. For an ideal lever: MA = VR = 4. This means a load 4 times the effort can be lifted.

Long Answer / Application Questions (4-6 Marks)

• Q: Explain the three classes of levers with one example each.
  Ans: Class 1: Fulcrum between load and effort. Example: See-saw, scissors. Class 2: Load between fulcrum and effort. Example: Wheelbarrow, nutcracker. MA > 1 always. Class 3: Effort between fulcrum and load. Example: Fishing rod, human forearm. MA < 1 always.
• Q: Draw a labelled diagram of a single fixed pulley and find its MA and VR.
  Ans: A single fixed pulley has VR = 1 (effort distance equals load distance). For ideal pulley, MA = VR = 1. It does not multiply force but changes the direction of effort (pulling down is easier). In practice, MA < 1 due to friction.
• Q: In a pulley system with 4 pulleys, a load of 200 N is raised. Find the effort needed if efficiency is 80%.
  Ans: VR = n (number of pulleys) = 4. Efficiency = MA/VR × 100. 80 = MA/4 × 100. MA = 3.2. MA = Load/Effort. 3.2 = 200/E. Effort E = 200/3.2 = 62.5 N.

Exam Tips for This Chapter

• Revise all definitions and laws from Machines — they are commonly asked as 1-2 mark questions
• Practice diagrams related to Machines — neat labelled diagrams carry 2-3 marks
• For numericals, always show formula → substitution → answer with correct units
• Previous year analysis shows Machines carries 8-12 marks in the board exam