Weber Liu 10.3 Science

Acceleration of a 50g weight affected by gravity

AimTo analyse a ticker tape and calculate acceleration.

Relevant theory- (Change in velocity)/ (Change in time) = Acceleration. - Gravity = 9.8ms-2

- Australia A.C is 50 Hz (Changes direction 50 times per second). It will make 50 dots a second, so every 5 dots is equivalent to 0.1 seconds

AbstractThe main objective of this experiment was to find the speed of the downwards acceleration on a 50g weight caused by Earth’s gravitational pull. The weight pulled a piece of paper, which had been threaded in between a ticker timer, connected to an A/C power supply with a frequency of 50Hz (5 ticks per 0.1 seconds). The speed of acceleration increased at a near-constant rate of approximately 38ms-2. This results of our experiment showed that we did not reach the speed of acceleration of gravity (9.8ms-2), which could have been due to factors such as friction.

IntroductionThis experiment of finding the acceleration of a 50g weight being dropped may be used to test the accuracy of the theory that gravity’s acceleration is 9.8ms-2. As the mass is affected by gravity, this force is used to pull the tape through the ticker timer, which is used to record the speed and acceleration of the mass. It is hypothesised that the acceleration of the mass will be will be equal to, or less than the acceleration that of gravity, as friction plays a main role in the setup of this experiment.

Risk AssessmentRisk Chance of risk

occurringHow to counter risk

Dropping weight on foot Medium Wear leather shoes; Stay out of the way of the weight

Receiving an electric shock Medium Wear insulated gloves; Do not touch uninsulated areas of wires; Keep power off until experiment has been set up and checked.

Paper cut from ticker tape Low Have first aid kit ready.

Weber Liu 10.3 Science

Material/Equipment- Tape- Ticker timer- Power Supply (A/C)- String- Bench Pulley- 50g Weight- Sticky tape

Method

Method for setting up experiment- Set up equipment as shown in diagram- Thread tape through timer- Test timer- Attach string to ticker timer- Thread string through bench pulley- Attach weight to string- Turn ticker timer on and allow weight to fall- Analyse tape

Method for analysing tape- Rule a line every 5 dots, starting from the starting location of the ticker timer- Measure the distance between every line ruled, and tabulate data (Time, Distance, Velocity)- Graph Velocity and time- Find the line of best fit- Find the gradient of the line of best fit (Acceleration)

Diagram

Weber Liu 10.3 Science

Weber Liu 10.3 Science

Time (s) Distance (m) Velocity (ms-1)0 0 0

0.1 0.034 0.34

0.2 0.095 0.950.3 0.133 1.13

0.4 0.153 1.530.5 0.187 1.87

0.6 0.187 1.87

Gradient =

(Y1 – Y2) / (X1 – X2)= (1.13 – 0.75) / (0.3 – 0.2)= 0.38/0.1= 3.8Acceleration = 3.8ms-2

Discussion/EvaluationThrough the results obtained from the experiment, the acceleration of a 50g mass dropping was found to be significantly lower than the acceleration of gravity. The results showed that the mass accelerated at a constant 3.8ms-2, whilst gravity accelerates at 9.8ms-2. These results support the hypothesis, and showed that a 50g mass does in fact accelerate slower than gravity, yet this does not mean it defies gravity. This expected result is due to friction, a force which slows down speed or acceleration. Friction within the experiment, found in the bearing of the pulley, the string through the pulley, and the ticker tape within the ticker timer is the main reason behind the loss of acceleration.

The validity of this experiment is poor as there are outlying points within the graph, and the line of best fit does not go through every point and this experiment was not very accurate as it was only taken once, so a constant recurring result could not be found.

For a better, more accurate and valid result, this experiment should be taken multiple times, and all the scores should be complied together and averaged. The outlying scores should be excluded as they are evidence of a faulty experiment. Through repeating a test multiple times, the scores should eventually become more accurate, and more valid.

ConclusionWe found that the acceleration of a 50g mass was 6ms-2 less than the acceleration of gravity, and 3.8ms-2. These results show that when dropping anything, so long as there is friction, the acceleration of that item will not be equal to the acceleration of gravity.