Year 9 Science · Unit 4 · Lesson 17

Balanced and Unbalanced Forces

Foundation Worksheet

Name
Date
Class

Learning Goals

Warm Up

Sort it!

Write each scenario from the pool into the correct category box below.

Book sitting on a shelf Car speeding up from traffic lights Skydiver at terminal velocity Rocket launching from a pad Helicopter hovering in place Ball decelerating after a kick Swimmer moving at constant pace Elevator accelerating upward

Balanced forces (net force = 0)

Unbalanced forces (net force ≠ 0)

Your Turn

True or False? Fix the false ones

Circle T or F for each statement. If the statement is false, rewrite it correctly on the line below.

Balanced forces always mean that the object is stationary and not moving.

Correct it:

T
F

Unbalanced forces cause an object to accelerate — it speeds up, slows down, or changes direction.

Correct it:

T
F

Terminal velocity occurs when gravity becomes zero as the falling object gets too fast.

Correct it:

T
F

A car moving at constant speed on a straight road has balanced forces acting on it.

Correct it:

T
F

Show What You Know

1. A book rests on a table. Name the two forces acting on the book, state the direction of each, and explain why the book does not move.

Recall 2 marks

2. A skydiver opens her parachute and eventually reaches terminal velocity. Describe what happens to the air resistance force and the net force as she goes from free fall to terminal velocity.

Recall 2 marks

Wrap Up

In one sentence, what was the main idea of this lesson?

HSCScience · Year 9 Science · Unit 4 · Lesson 17 · Foundation Worksheet