Gravity and light
What actually changes a pendulum's swing?
Does mass or length change the time for ten swings?
Watch first
Find out why weight is really a force, and mass is not.
What you need
Tick each one as you find it — 0 of 4 ready.
Plan the fair test
- Change: Mass in the first test, string length in the second
- Measure: Time for ten swings, in seconds
- Keep the same: The size of the pull-back, and only changing one thing at a time
Objectives this evidences
- Understand gravity force, weight and mass, and the relationship between them on Earth and other bodies
Do it, one step at a time
Step 1 of 4
- Step 1. Hang a weight on 30 cm of string and time ten full swings. Repeat three times and take a mean.
- Step 2. Swap in a heavier weight, keeping the string exactly 30 cm. Time ten swings again.
- Step 3. Now go back to the first weight and try 15 cm, 30 cm and 45 cm of string.
- Step 4. Compare your two sets of results and decide which variable actually matters.
What should happen
Mass makes almost no difference; longer string means slower swings.
Think about: Why time ten swings and divide, rather than timing one?
Write up your result
A sentence or two is enough to save it.
The lessons behind this practical
Each one opens with the same short film, and the film has a written transcript underneath if reading is easier than watching.
Now the quiz for this topic
Questions come from the lessons behind this practical, so nothing is asked that has not been taught.
Quiz
Gravity and light quiz
4 questions from the lessons in this stage. No timer, and you can try again as many times as you like.