CHAPTER: Simple Machines Class 6

1. What is work?

Ans: After applying force on a body moves or change its position is called work.

2. What is the S.I. unit of work?

Ans: Joule (J)

3. What is energy?

Ans: Energy is the ability to do any work.

S.I. unit of energy is Joule (J).

4. Define mechanical advantage.

Ans: The ratio of load lifted and effort apply of a machine is called mechanical advantage of that machine.

★ It has no any Unit.

5. What is effort arm?

Ans: The distance between fulcrum to effort is called effort arm.

6. What is load arm?

Ans: The distance between fulcrum to load is called load arm?

7. What is the machine? Give example.

Ans: A machine which makes our work easy. Ex- Nut Crackers.

8. How many types of machines?

Ans: Two types of machine - (i) Simple machine ( Scissors)

(ii) Complex machine ( Car)

9. What is a simple machine? Give example.

Ans: Simple machines are basic tools for applying a force and doing work. Ex- Scissors.

10. What is a complex machine? Give example.

Ans: Complex machines are made by combining different types of simple machines. Ex - Car.

11. How many types of simple machines? Name them.

Ans: There are six types of simple machines.

(i) Lever - See-saw.

(ii) Inclined plane - Stair.

(iii) Screw - Nut-bolts.

(iv) Wedge - Axe.

(v) Pulley - Crane.

(vi) Wheel and Axle - Door knobs.

12. Define lever.

Ans: A lever is a simple machine that is used to lift heavy objects by small force.

13. How many types of lever? Give example.

Ans: There are three types of levers.

(i) Class 1 Lever (Scissors)

(ii) Class 2 Lever ( Wheel Barrow)

(iii) Class 3 Lever ( Tongs)

14: What is the mechanical advantage of class 1 lever?

Ans: Mechanical advantage of Class 1 is >1,<1,=1

15: Mechanical advantage of class 2 lever is always greater than 1 ( >1), why?

Ans: Because effort arm always greater than load arm.

16: What is the Mechanical advantage of Class - 3 lever? Why?

Ans: M.A. of Class -3 lever is always <1.

17. On which basis levers are divided?

Ans: The levers are divided on the position of fulcrum, load, and effort.

18. What is a fulcrum?

Ans: Fulcrum is a fixed point on which the rod ( lever) moves freely.

19. What is an inclined plane?

Ans: Inclined plane is a simple machine it has slopping surface. Ex - Ramp.

20: Find the M.A. of Inclined Plane.

Ans: The ratio of length ( Inclined Plane) to height ( Vertical).

21. What is a screw?

Ans: An inclined plane wrapped surround a nail called a screw. Ex - Nut-bolt.

22. What is a wedge?

Ans: Two inclined planes joining together ( back to back) is called a wedge. Ex - Axe, Knife.

23. What is a pulley?

Ans: A pulley which has a wheel with grooves, on which a chain moves to lift the load. Ex - Crane.

24: How many types of Pulleys?

Ans: 1) Fixed Pulley Ex.- Using well

2) Movable Pulley Ex.- Crane

25: What is the block and tackle system of the pulley?

Ans: Arrangement of several Pulleys to lift a heavy load.

26: What is the efficiency of a machine?

Ans: The ratio between work done by a machine and work done on a machine is called the efficiency of a machine.

27: Why is the efficiency of a machine always less than 100%? Ans: The efficiency of a machine always less than 100% because friction between parts of machine. Also produce heat and reduce the performance of the machine. So output energy is always less than the input energy.

28: How do you take care of machine?

Ans: 1) Cover machines if not used.

2) Regularly oil or grease the parts of machine.

3) Not use machines with overloaded.

4) Keep the machine away from dirt and water.

29. What are Wheel and Axle?

Ans: A wheel and Axle is the arrangement of wheel that attached to an axle (rod). Ex - Door-knob.

30. Write the difference between Class - 1 lever and class - 2 lever.

Ans: