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Lesson 18 of 84 · Energy
ExperimentBalanced and Unbalanced Forces
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
- string
- weights
- tape
- ruler
- cardboard
- marbles
Safety First
- Use materials only as directed in the experiment.
- Keep small objects away from young children.
- Work in a well-ventilated area when using vinegar or other strong-smelling substances.
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 3What do balanced forces result in?