P1: Investigating motion on an inclined runway

Independent variable

height of the ramp

Dependent variable

average speed of the marble down the ramp

Controlled variable

surface of the ramp

Apparatus

• Wooden ramp about 120 cm long

• Blocks of wood from about 5 cm high to about 15 cm high

• Metre stick – to measure height of block and distance on runway

• Pencil

• Stopwatch

• Marble

Method

1. Set up ramp against wooden block

2. Using ruler, draw two pencil lines in the ramp, one at top and other at the bottom

3. Measure the distance, x between these two lines (1m)

4. Measure the height of the ramp, h

5. Allow marble to roll down ramp, starting from rest at upper line and finishing at lower line

6. For each height h, time motion three times using stop watch and record the results in table

7. Calculate average time, t

8. Average speed is equal to x/t

Graph

• average speed (y axis)

• height, h (x axis)

• line of best fit is curve through origin of decreasing gradient

• shows average speed is not proportional to h, but increases non-linear

Results

as height of runway increases, average speed will also increase

Justification

• as height increases GPE of marble will also increase

• when moves down GPE is converted to kinetic energy

• a greater amount of kinetic energy at bottom will have greater speed

Error

main error is reaction time using the stop clock

Safety

• make sure the marble doesn’t fall on to the floor

• secure the runway with a clamp

• wear safety goggles