Class 10 Machines Mock Test (ICSE)

Topics in Machines

• Mechanical advantage, velocity ratio and efficiency
• Levers of three classes
• Single fixed and movable pulleys
• Block and tackle system
• Relation between MA, VR and efficiency

Machines practice questions with answers

1. Q1Multiple choice·1 mark
   Which of the following expressions correctly relates mechanical advantage ($\text{MA}$), velocity ratio ($\text{VR}$), and efficiency ($\eta$) of a machine?

   1. (a)$\eta = \frac{\text{MA}}{\text{VR}}$
   2. (b)$\eta = \text{VR} \times \text{MA}$
   3. (c)$\text{VR} = \text{MA} \times \eta$
   4. (d)$\text{MA} = \frac{\text{VR}}{\eta}$
   Show answer and step marks

   1. Correct option: (a) $\eta = \frac{\text{MA}}{\text{VR}}$+1

   Answer: (a)
2. Q2Multiple choice·1 mark
   In a block and tackle system consisting of a total of $5$ pulleys (with $3$ pulleys in the upper fixed block and $2$ pulleys in the lower movable block), the velocity ratio of the system is:

   1. (a)$2$
   2. (b)$3$
   3. (c)$6$
   4. (d)$5$
   Show answer and step marks

   1. Correct option: (d) $5$+1

   Answer: (d)
3. Q3Multiple choice·1 mark
   The ideal mechanical advantage of a single movable pulley when used in conjunction with a single fixed pulley is:

   1. (a)$3$
   2. (b)$1$
   3. (c)$2$
   4. (d)$0.5$
   Show answer and step marks

   1. Correct option: (c) $2$+1

   Answer: (c)
4. Q4Multiple choice·1 mark
   A machine has a velocity ratio of $4$ and an efficiency of $75\%$. The mechanical advantage of the machine is:

   1. (a)$4$
   2. (b)$3$
   3. (c)$5.33$
   4. (d)$300$
   Show answer and step marks

   1. Correct option: (b) $3$+1

   Answer: (b)
5. Q5Short answer·2 marks
   A load of $150\text{ N}$ is applied at a distance of $40\text{ cm}$ from the fulcrum of a class-II lever. If the effort is applied at the other end at a distance of $100\text{ cm}$ from the fulcrum, calculate the effort required and the mechanical advantage of the lever.
   Show answer and step marks

   1. Applying the principle of moments: $\text{Effort} \times \text{Effort arm} = \text{Load} \times \text{Load arm}$ i.e., $E \times 100 = 150 \times 40$.+1
   2. Effort $E = \frac{150 \times 40}{100} = 60\text{ N}$.+0.5
   3. $\text{MA} = \frac{\text{Load}}{\text{Effort}} = \frac{150}{60} = 2.5$.+0.5

   Answer: Effort = $60\text{ N}$, Mechanical Advantage = $2.5$
6. Q6Long answer·4 marks
   A load of $180\text{ N}$ is lifted using a single movable pulley supported by a fixed pulley. An effort of $100\text{ N}$ is applied to lift the load through a vertical height of $2\text{ m}$. (a) State the velocity ratio of this system and calculate the distance through whom the effort moves. (b) Calculate the mechanical advantage of the system. (c) Find the percentage efficiency of the pulley system.
   Show answer and step marks

   1. (a) The fixed pulley only changes the direction of the effort, so the velocity ratio of the single movable pulley system is $\text{VR} = 2$.+1
   2. (a) Distance moved by the effort $= \text{VR} \times \text{load distance} = 2 \times 2\text{ m} = 4\text{ m}$.+1
   3. (b) Mechanical advantage $(\text{MA}) = \frac{\text{Load}}{\text{Effort}} = \frac{180\text{ N}}{100\text{ N}} = 1.8$.+1
   4. (c) Efficiency $(\eta) = \frac{\text{MA}}{\text{VR}} \times 100 = \frac{1.8}{2} \times 100 = 90\%$.+1

   Answer: (a) $\text{VR} = 2$, Distance = $4\text{ m}$ (b) $\text{MA} = 1.8$ (c) $\eta = 90\%$

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