Simple Machines
Section I
A. Choose the correct option.
1. A machine is a tool which
a. saves our time. [ ]
b. makes work easier. [ ]
c. needs less effort. [ ]
d. all of these. [✓]
2. Example/s of simple machine
a. pulley. [ ]
b. wedge. [ ]
c. lever. [ ]
d. All of these. [✓]
3. Example of class one lever is
a. wheelbarrow. [ ]
b. nutcracker. [ ]
c. seesaw. [✓]
d. tweezers. [ ]
4. Which of the following is an example of a wedge?
a. stapler. [ ]
b. screw. [ ]
c. knife. [✓]
d. Nutcracker. [ ]
5. A pulley consist of
a. a wheel. [✓]
b. a modified inclined plain. [ ]
c. a lever. [ ]
d. an inclined plain. [ ]
B. Choose the correct answer.
1. A simple machine has (many/few) parts.
2. The fixed point around which the rod moves is called the (effort/fulcrum).
3. A pair of scissors is an example of class (one/two) lever.
4. In a pulley the wheel rotates around the (axle/fulcrum).
5. The movable pulley has (fixed/movable) axle.
C. Give two example of the following.
1. Simple machines
= Wheelbarrow; Lever.
2. Class-one lever
= Seesaw; Crowbar.
3. Class-two lever
= Bottle-opener; Nutcracker.
4. Class-three lever
= Fishing rods; Tweezers.
5. Wheel and axles
= Steering wheel; Doorknob.
6. Inclined Plane
= Hospital ramp; Playground slide.
D. Name the following.
1. Two types of machines.
= Simple and complex.
2. Three kinds of lever.
= Class-one; Class-two; Class-three.
3. The external force that has to be applied on a lever at a particular place.
= Effort.
4. A lever in which the load is situated between the fulcrum and effort.
= Class-two lever.
E. Name the type of simple machines used for doing the following activities.
1. To carry load.
= lever.
2. To open a bottle.
= Bottle opener.
3. To break the outer covering of walnut.
= Nutcracker.
4. Lifting a heavy load using a crane.
= Pulley.
5. A rod of catching fish.
= Class-three lever.
6. A slope to move a heavy load.
= Inclined plain.
Section II
F. Short answer questions.
1. Why are machines used?
= A machine is at tool that makes our easier. It helps us to overcome a large force(required to move a load) by applying a lesser force (called effort).
2. What is a lever? Name the three types of levers.
= A lever is rigid bar resting on a pivot. It is used to move a heavy load with one end when pressure is applied on the other end.
The three types of lever are -
i) Class-one lever. Example- Scissors; Seesaw; Crowbar etc.
ii) Class-two lever. Example- Wheelbarrow; Bottle opener etc.
iii) Class-three lever. Example- Fishing rods; Tweezers; Tongs etc.
3. Write a short note on pulley.
= A pulley is a simple machine used to lift heavy objects. A pulley consists of a wheel with a grooved rim and a rope, chain, or belt wound around it. The wheel rotates around an axle.
4. Define wedge.
= A wedge is a simple machine that has a long triangular shape with one broad or blunt end, and one sharp end. The sharp end is used to cut or slice objects. A wedge may also be formed when two inclined planes are joined together. The head of an axe and the blade of a knife are examples of wedge.
G. Long answer questions.
1. What is a simple machine? Name some simple machines.
= A simple uses a single applied force to get the work done. A simple machine has very few parts. A wheelbarrow is an example of a simple machine.
A lever, pulley, wheel and axle, wedge, screw and an inclined plane are some simple machines.
Lever: A lever is a rigid bar resting on a pivot. It is used to move a heavy load with one end when pressure is applied on the other end.
A lever consists of the following parts:
Fulcrum- The fixed point around which the rod moves is called the fulcrum(F).
Load- The object on which the work is to be done is called the load(L).
Effort- The external force that needs to be applied on a particular place of the rod to do its work is called effort(E).
Pulley: A pulley is a simple machine used to lift heavy objects. A pulley consists of a wheel with a grooved rim and a rope, chain, or belt wound around it. The wheel rotates around an axle.
Wheel and axle: A wheel and axle is a simple machine made up of a wheel rigidly attached to a rod (called axle). A steering wheel and a doorknob are example of wheel and axle. When one rotates the wheel, the axle also rotates.
Inclined Plan: An Inclined Plain is a tilted surface of a slope used to move a heavy load with less effort. Ramps in hospitals and slides on the playground are examples of inclined plane.
Screw: A screw is a modified inclined plane. It has a groove of its head into which the tip of a screwdriver fits easily. It is used to hold things tightly together. Screws are used in objects such as light bulbs. Big screws, called screw jocks, are used to lift cars and other heavy objects such as logs of wood and iron plates.
Wedge: A wedge is a simple machine that has a long triangular shape with one broad or blunt end, and one sharp end. The sharp end is used to cut or slice objects. A wedge may also be formed when two inclined planes are joined together. The head of an axe and the blade of a knife are examples of wedge.
2. What is a pulley? Explain different types of pulleys with examples.
= A pulley is a simple machine used to lift heavy objects. A pulley consists of a wheel with a grooved rim and a rope, chain, or belt wound around it. The wheel rotates around an axle.
Pulleys are of the following two types:
Fixed Pulley: This type of a pulley has a fixed axle. A fixed pulley makes work easier by changing the direction of the force. This type of a pulley is used to draw a bucket of water from a well.
Movable Pulley: This type of a pulley has a free or movable axle. It is used along with a fixed pulley. For example, a crane uses both fixed and movable pulleys to lift loads.