Available Answers

1. 1.

   Choose the correct answer :

   1. Efficiency of a machine is −
      1. output × input
      2. output/input
      3. input/output
      4. output + input
   2. Levers are of −
      1. one type
      2. two types
      3. three types
      4. four types 
   3. For levers of first order −
      1. MA = 1
      2. MA > 1
      3. MA < 1
      4. all of these
   4. For levers of third order −
      1. MA = 1
      2. MA < 1
      3. MA > 1
      4. MA = 0
   5. Doorknob is an example of a/an −
      1. inclined plane
      2. wheel and axle
      3. wedge
      4. screw
   6. A wirecutter is an example of a −
      1. level of first order
      2. level of second order
      3. level of third order
      4. None of these
   7. In case of a movable pulley −
      1. MA = 1
      2. MA > 2
      3. MA < 1
      4. MA = 2
   8. Mechanical advantage of a machine is −
      1. Load × Effort
      2. Load / Effort
      3. Load + Effort
      4. Effort / Load
2. 2.

   Fill in the blanks :

   1. A jack is used to ________________________ force.
   2. A nutcracker is a lever of ____________________________ order.
   3. In levers of first order ___________________ is in between load and effort.
   4. Levers of second order act as _________________ multiplier.
   5. A single fixed pulley is used to ______________________ the direction of applied force.
   6. Mechanical advantage of a machine is _____________________ than 100 per cent.
   7. Chisel is an example of ________________.
   8. Steering wheel is an example of __________________ .
   9. A crowbar is a lever of ____________________ order.
   10. Moving parts of a machine are lubricated to ______________________ friction.
3. 3.

   Write True (T) or False (F) against the following statements :

   1. A bicycle is an example of a simple machine.
   2. A staircase is an example of a screw.
   3. Levers of third order help us to multiply force.
   4. A nail is an example of a lever.
   5. The ratio of load to the effort is called velocity ratio of a machine.
   6. Friction reduces efficiency of a machine.
   7. A doorknob is an example of a screw.
   8. A screw driver is an example of a wheel and axle.
   9. The efficiency of a machine is always greater than 100 per cent.
   10. Single fixed pulley is an example of a lever of second order.
4. 4.

   Match the following :

   Column  A	Column  B
   1. Load/Effort	a. A pair of fire tongs
   2. Output/Input	b. Bottle opener
   3. Level of first order	c. Crowbar
   4. Lever of second order	d. Mechanical advantage
   5. Lever of third order	e. Efficiency
   6. Inclined plane	f. Changes direction of effort
   7. Screw	g. Knife
   8. Wedge	h. Screwdriver
   9. Wheel and axle	i. Ramp
   10. Single fixed pulley	j. Bolt

    

5. 5.

   With proper reasoning, choose the odd one out :

   1. fire tong, bottle opener, see-saw, bolt
   2. inclined plane, screw, wedge, watch
   3. bottle opener, wheelbarrow, nutcracker, human forearm
   4. ramp, staircase, wheel, wooden plank
   5. crowbar, a pair of scissors, lemon squeezer, beam balance
6. 6.

   Mention the class of lever to which the following machines belong :

   1. Wheelbarrow
   2. Nutcracker
   3. A pair of pliers
   4. A pair of scissors 
   5. A human forearm
   6. An oar of the boat while rowing