Balanced and Unbalanced Forces

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Forces diagram showing balanced and unbalanced forces

🎯 WALT (We Are Learning To)

Understand the difference between balanced and unbalanced forces and their effects on motion.

Success Criteria:

• I can identify balanced and unbalanced forces

• I can predict how forces affect motion

• I can apply force concepts to real-life situations

Key Concepts:

Balanced Forces: Equal forces acting in opposite directions. Objects remain at rest or move at constant speed.

Unbalanced Forces: Unequal forces that cause objects to accelerate, decelerate, or change direction.

📚 Part 1: Understanding Forces

1. When forces are balanced, what happens to an object's motion?

The object speeds up

The object slows down

The object stays at rest or moves at constant speed

The object changes direction

2. Which of these situations show unbalanced forces? (Tick all that apply)

A car accelerating from traffic lights

A book sitting on a table

A ball falling through the air

A bike moving at constant speed on flat ground

3. A tug-of-war team pulls with 500N to the left. The other team pulls with 500N to the right. These forces are _____________ because _____________.

✏️ Part 2: Real-Life Applications

4. Foundation Level: Look at a person sitting in a chair. Name the two main forces acting and explain why the person doesn't fall through the floor.

5. Standard Level: A skydiver jumps from a plane. Describe how the forces change from when they first jump until they reach terminal velocity (constant falling speed).

6. Extension Challenge: A rocket launches into space. The rocket engines produce 2,000,000N of upward force. If the rocket weighs 1,800,000N, calculate the net force and explain what happens to the rocket's motion. Show your working.

7. Draw and label a force diagram showing a car travelling at constant speed on a motorway. Include all forces acting on the car.

8. Think-Pair-Share: Explain to a partner why a shopping trolley is easier to push when it's empty compared to when it's full of groceries. Write your explanation here: