Science Fair

Grown-ups

Does a heavier pendulum swing faster?

5th–8th grade · 1 day of testing · free · ages 10 to 14 · 40 minutes a sitting

  • 👶 Small parts
What you need for the pendulum weight and swings project: string or yarn, pennies, a pencil, a stopwatch or a kitchen timer

My hypothesis

If I change how many pennies hang on the string, then how many swings it makes in 30 seconds will ______, because ______.

You fill in the blanks. Think about whether heavy things fall faster than light things. A guess is a good because: the test finds out.

Change, measure, keep the same

CHANGE

how many pennies hang on the string: 2 pennies, 5 pennies, 10 pennies, 20 pennies

MEASURE

how many swings it makes in 30 seconds, in swings

KEEP THE SAME

  • the same string, 40 cm long
  • letting go from the same distance out to the side
  • counting for the same 30 seconds
  • the same pencil to hang it from

Scientists call the thing you change the independent variable and the thing you measure the dependent variable. The things you keep the same are the controls: if one of them changed too, you wouldn't know which change made the difference. Try each of the 4 levels 3 times.

What you need

  • String or yarn: about 60 cm
  • Pennies: 20
  • A pencil
  • A stopwatch or a kitchen timer
  • 🩹 Tape
  • 📏 A ruler

Steps

  1. Tape a pencil to the edge of a table so it sticks out.
  2. Tape 2 pennies together into a little stack: that's the lightest weight.
  3. Tape a string to the stack and hang it from the pencil, 40 cm from the pencil to the pennies.
  4. Pull the pennies out to the side until the string is straight, and let go.
  5. A helper times 30 seconds while you count the swings: over and back is one.
  6. Write the count down, then do it two more times.
  7. Tape on more pennies to make 5, and check the string is still 40 cm long.
  8. Count the swings three times with 5 pennies, then with 10, then with 20.
  9. Find the mean for each weight and draw a line graph.

Every step is one you can do yourself, with a grown-up nearby. Write each number down straight away, in the table below, so nothing is lost.

Your results table

MY RESULTSPeabody 🦉 peabody.kids/science-fair

Name ______________________ Fair day ____________

Question: Does a heavier pendulum swing faster?

I changed: Pennies on the string   I measured: how many swings it makes in 30 seconds (swings)

Pennies on the stringTry 1 (swings)Try 2 (swings)Try 3 (swings)Mean
2 pennies
5 pennies
10 pennies
20 pennies

MY GRAPH (a line graph: pennies on the string along the bottom, swings up the side)

What I noticed: ______________________________________________

From 4th grade, add the tries for each level and divide by how many there were: that's the mean, and it goes in the last column. Then draw a line graph, because the thing you change is a number that goes up.

📊 Make my graph🖨 Print the whole packet (9 pages)

Why it works

Gravity pulls harder on a heavy weight, but a heavy weight is also harder to get moving, so the two cancel out. A heavy and a light weight on the same string therefore swing at nearly the same rate. The length of the string is what really sets the swing, so your counts should stay close together.

Going further (7th and up): Change a second thing: keep 10 pennies and try strings 20, 40 and 60 cm long, then graph swings against length beside this graph.

Board layout

MY BOARD · 36 × 48 in tri-foldPeabody 🦉 peabody.kids/science-fair
  1. ❓ Question (10 × 8 in): Does a heavier pendulum swing faster?
  2. 💭 Hypothesis (10 × 9 in): If I change how many pennies hang on the string, then how many swings it makes in 30 seconds will ______, because ______.
  3. 🧺 Materials (10 × 12 in): 4 things: see your list.
  4. 🪜 Steps (22 × 9 in): 9 steps, three tries at each level.
  5. 📊 Results (22 × 16 in): Your table (Pennies on the string down the side, tries across) and your line graph.
  6. ✅ Conclusion (10 × 14 in): My hypothesis was right / partly right / not right. I know because…

Materials to list: String or yarn; Pennies; A pencil; A stopwatch or a kitchen timer.

Bring photos or drawings of your test. Nothing wet, hot, powered or alive on the table.

This project at your grade

4th–6th gradeTries: three at each level. The table: units in the header and a mean column. The graph: a bar graph, or a line for a number that grows. The conclusion: right, partly or not, and the numbers that show it.
7th grade and upTries: three or more at each level. The table: a mean for every level of both tests. The graph: a graph with two lines or two sets of bars. The conclusion: the numbers, what might have gone wrong, and a next question. Second variable: keep 10 pennies and try strings 20, 40 and 60 cm long, then graph swings against length beside this graph.

Every grade this project fits works out a mean. See every project for 5th grade, or print a blank results table.

What a judge will ask

  • What did you change, and what did you measure? I changed how many pennies hang on the string and measured how many swings it makes in 30 seconds, in swings.
  • What did you keep the same, and why does that matter? I kept the same string, 40 cm long and letting go from the same distance out to the side the same, so the only difference was how many pennies hang on the string.
  • How many times did you test it? 3 times at each of my 4 levels.
  • If you did it again, what would you change or test next? I'd keep 10 pennies and try strings 20, 40 and 60 cm long, then graph swings against length beside this graph.

Make it yours

Keep this project on this device and Peabody counts down to your fair day, with a plan for each day. Nothing is sent anywhere.

Try next

👨‍👩‍👧 For grown-ups and teachers: how much to help, the safety rules, and running a school fair. Science fair v0.16.1 · Checked .

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