Science 7–10 · Year 8
Marble on a ramp: release height, speed at the bottom and the distance a cup is pushed
Physical sciences — Change, content group Energy transfers (NSW Stage 4 focus area)
This site has no interactive model of its own. Where a step or a material names a Concept Studio model, simulation or tool, it has not been built; an external simulation a step names (for example PhET) is not part of this site.
The idea
The higher a ball starts on a ramp, the more gravitational potential energy it stores and the more kinetic energy it has at the bottom, which shows up as a faster ball and a further-pushed cup.
What you need
- grooved ramp (curtain track or a folded card channel) 1.0 m, 1
- glass marbles 16 mm, 3
- paper cup with a 3 cm doorway cut in the rim, 1
- metre rule and 30 cm rule, 1 each
- light gate with timer, or a phone with slow-motion video, 1
- electronic balance, 1
How to do it
- Set the ramp so it runs smoothly onto a flat, level bench. Place the cup at the ramp foot with its doorway facing the ramp; mark its starting position.
- Release a marble from a point 5.0 cm above the bench (measured vertically) and record how far the cup slides. Return the cup to the mark. Five trials, average.
- Repeat for release heights of 10.0, 15.0, 20.0 and 25.0 cm.
- Plot cup distance against release height and describe the relationship.
- Place the light gate at the ramp foot and measure the marble's speed for each release height (speed = marble diameter divided by transit time).
- Plot speed against height and describe how the speed changes when the height is doubled and when it is quadrupled.
What you should see
Cup distance rises in proportion to release height, so the graph is close to a straight line through the origin: a higher start stores more gravitational potential energy, so the marble reaches the bottom with more kinetic energy and pushes the cup further. Speed at the bottom also rises with height but less steeply: the model below gives about 0.84 m/s from 5.0 cm and 1.67 m/s from 20.0 cm, so four times the height gives twice the speed. Measured speeds are often a little lower than these because of friction and the way the marble rolls in the groove.
What changes
- What you change
- vertical release height of the marble (cm)
- What you measure
- distance the cup slides (cm) and marble speed at the ramp foot (m/s)
- What you keep the same
- same marble
- same cup and bench surface
- cup replaced on the same mark
- release from rest
Common misconceptions
Each of these ideas is wrong, and the activity is a chance to test it.
- The marble's speed at the bottom depends on the ramp's steepness rather than its height.
- A heavier marble reaches the bottom faster.
- Energy is created by the ramp.
Safety card
Hazards
- marbles on the floor causing slips
Controls
- catch marbles in a tray
- pick up strays at once
Note
No hazardous chemicals or naked flames are used. Complete the school's risk assessment for the activity before the lesson; the NSW Department of Education Science safety and compliance page points to CSIS 1.7 (Risk assessment – a pre-requisite for risk control) for how to carry it out.
Curriculum references
The NSW syllabus outcomes and Australian Curriculum v9 codes this activity supports. They are references, not a verified or complete curriculum alignment.
- Science 7–10 Syllabus (2023)SC4-CHG-01SC4-WS-04SC4-WS-05SC4-WS-06
- Australian Curriculum v9AC9S8U05AC9S8I02AC9S8I04AC9S8I05
Sources
The pages the author read to write this activity.