Page 150 - Active Science 5 Ebook and Activity

Glossary

• Force : A push or pull applied to move an object.
• Energy : The capacity to do work.

• Machine : A device that does work.
• Fulcrum : The point of support in a lever.

• Lever : A rigid rod which can move about a fixed point.
• Inclined plane : A slope.

• Wedge : Two inclined planes joined together to form a sharp edge.
• Wheel and axle : A wheel mounted rigidly on an axle.

• Pulley : A wheel with a groove around which a rope is wound.

Practice Time

A. Tick the correct answer.

1. Work is said to be done __________________.
a. when an object changes its direction of movement
b. when an object stops moving
c. when an object moves from rest

d. in all the above cases
2. How can we increase the speed of doing work?
a. By increasing pressure b. By using a machine

c. By working hard d. By applying more and more force.
3. Very large stones can be lifted by using __________________.
a. a wedge b. a lever
c. an inclined plane d. a wheel

4. An example of wedge is __________________.
a. jack b. nail
c. blade d. pliers

5. Which action is not true for a lever?
a. Opening lids/caps b. Expanding things
c. Lifting weights d. Moving weights

6. A pulley helps to _________________.
a. open things b. push a load
c. lift a load d. cut things

B. Fill in the blanks.

1. Machines can be _____________ or _____________.
2. A pair of scissors is an example of a _____________ machine.

150 Active Science-5