Alternative Task 1 – Acceleration of free fall
The aim of this experiment is to graphically determine the value of the
acceleration due to the earth.
two electrical leads
brass masses or anything suitable
chair or lab stool.
1. Set up the equipment as shown in the diagram. You need to clamp the
ticker timer (shown face-on) to the table or bench and ensure the ticker
tape can thread through the ticker timer without a hitch.
2. Think about how you can minimise errors in your measurement(s).
3. Thread the ticker tape through the ticker timer.
4. Attach a brass mass to the end of the ticker tape.
5. Attach the electrical leads to the AC output connectors of the power pack
and set the voltage to 6 V AC.
6. Position brass masses high above the ground and near the ticker timer.
7. Turn on the power pack and ensure imprints are showing on the tape.
8. Release the brass masses.
1. On the ticker tape, mark the start of the motion (‘starting dot’) and count off
another five consecutive dots. This will be called an ‘interval’.
2. Construct a table to show the:
a) time of the interval (time elapsed between middle dot and ‘starting
dot’ in seconds)
b) length of the interval in metres
c) average speed in m s-1.
3. Calculate the time for the interval in seconds.
4. Measure the length of the interval in metres.
5. Calculate the average velocity during the interval in m s-1.
6. Count off the next five dots.
7. Repeat steps 3 to 6.
8. Graph velocity (y-axis) against time (x-axis).
Use the graph to find the value of the acceleration due to gravity.
(Hint: consider the gradient or slope of the graph).
State a conclusion for this experiment.
1. State the independent and dependent variables in this experiment.
2. Describe how you minimised errors in this experiment.
3. State the absolute errors for your measurements of time and length.
4. How well does your value for ‘g’ compare to the accepted value at sea
level on earth (9.80 m s-2)?
5. During a volleyball game the middle blocker jumps up and spoils the
opponent’s attacking shot. The ball ricochets directly upwards from a
height of 3.2 m at 10.0 m s-1. How long will it take the ball to fall down to
6. Suppose your ticker timer set up is taken to the moon where the
acceleration due to gravity at the surface is 1.60 m s-2. Describe what
effect this would have on the dot spacing and explain it using a motion