Work and Energy - 4th Science Term 1 Unit 3 - Questions and Answers

Work and Energy

Term 1 Chapter 3 | 4th Science

Evaluation I. Use the correct word to fill the blanks.

(Ramp, Simple machines, Work, Energy, Pulley)

• 1. Work is said to be done when a force is acting on it.
• 2. The ability to do work is Energy.
• 3. Pulley is a machine made up of wheel and rope.
• 4. Simple Machine help us to make work easier.
• 5. An example for inclined plane is Ramp.

II. Rearrange the letters and find out the names of the tools.

EDGEW    RLEVE    EWCRS

III. Match.

Match the items in the list below:

• 1. Class II lever - Drawing water
• 2. Pulley - Bicycle
• 3. Class I lever - Nut cracker
• 4. Wheel and axle - Wind
• 5. Renewable resource – Seesaw

Solution

Answer:

• 1. Class II lever - Nut cracker
• 2. Pulley - Drawing water
• 3. Class I lever - Seesaw
• 4. Wheel and axle - Bicycle
• 5. Renewable resource - Wind

IV. Classify the things below.

Class of Lever

• 1. Spade : III
• 2. Seesaw : I
• 3. Wheel barrow : II
• 4. Plier : III
• 5. Nail cutter : III

V. Answer the following.

• 1. What is the unit of energy?
  The unit of energy is Joule.
• 2. Name some simple machines.
  The pulley, wedge, inclined plane, screw, lever, wheel and axle are some simple machines.
• 3. What is a first order lever?
  When the fulcrum is between the effort and the load it is known as a first order lever.
• 4. Lemon juicer belongs to which type of lever? Why?
  Lemon juicer belongs to class II lever because the load (lemon) is between effort and fulcrum.
• 5. Define work.
  An action in which one exerts force to more an object is known as work.
• 6. Write any three types of energy.
  Chemical energy, electrical energy, thermal energy.

Think and say

Teacher: Yesterday I was walking back from school. I found some people working to lay the road. I found some items in that place. Can you say something about that place and the machines that were used there? Or Say something about the machines that were used. When can we say that work is done or not?

Answer:
Machines like road roller, crow bars, spades, pick axe and shovels are used. The shape of the road is changed by applying force. So we say that work is done.

Try to Answer

Observe the picture and put a tick (✓) if work is done and put a cross (x) if work is not done.

Try to Answer

Mention whether work is done or not in the following activity.

Observe the picture. Which is easier? Lifting the load with the help of a pulley or without a pulley?

Answer: Lifting the load with the help of a pulley is easier.

Observe the picture and discuss. Is lifting a box is easier than rolling it on a ramp?

Answer: Rolling a box on a ramp is easier than lifting it.

Try to Answer

Identify and mention the types of simple machines.

Try to Answer

Complete the table.

• 1. Pulley: To draw water from wells
• 2. Wheel and axle: To drive a bicycle
• 3. Wedge: To split materials
• 4. Inclined plane: Rolling things up or down
• 5. Lever: To increase the force given
• 6. Screw: To hold objects together

Try to Answer

Name the load, effort and fulcrum.