Balanced and Unbalanced Forces (Part 2)

What You'll Learn

Balanced forces are equal in size and opposite in direction, so an object stays still or moves at constant speed. Unbalanced forces cause an object to accelerate or change direction.

Key Words

simple machine
lever
pulley

Materials Needed

stopwatch
pencils
toy cars
ramps

Safety First

Dispose of materials properly after the experiment.
Handle glass items carefully to avoid breakage.

Steps

Step 1 — Read

Read the introduction and identify the main idea of this lesson.

Step 2 — Do

Test friction: pull a weighted box across 4 surfaces (carpet, tile, sandpaper, foil). Use a spring scale to measure the force needed for each.

Step 3 — Observe

Look for patterns in your observations.

Step 4 — Record

Make a graph or chart showing your results.

Check Your Understanding

Question 1

1 of 3

What do balanced forces result in?