Height of sand is measured with the same ruler used in the experiment and marked out with a marker. The volume of same is measured by pouring it into a beaker and then weighed on an electronic weighing balance for further accuracy. The diameter of the pendulum ball was measured before the start of the experiment and noted down.
Apparatus:
- Pendulum Ball x 1
- 1m Ruler x 1
- Plastic box x 1
- Sand
- 500ml Beaker x 1
- Vernier Caliper x 1
- Retort stand
- Whiteboard Marker
- Tissue
Method:
- Lay out newspaper on the bench/work area
-
Measure out 250cm3 of sand using the beaker
- Pour the sand into the plastic container
- Smoothen the sand with a tissue so that it is leveled
- Measure the height of the sand and mark it out with the marker on the container
- Set up the rest of the experiment as drawn on the previous page
- Hold the pendulum ball at a height of 10cm with the bottom of it on the 10cm mark
- Drop the pendulum ball onto the sand
- Remove the pendulum ball carefully so as not to destroy the crater made in the sand
- Using a vernier caliper, measure the depth of the crater
- Record the reading down
- Repeat steps 4-10 for heights of 20cm, 30cm, 40cm, 50cm, 60cm, 70cm, 80cm, 90cm and 100cm
- Repeat the whole experiment once
Results:
Evaluation
Reliability of method:
From the table of results, it can be observed that some results in the first set of data differ greatly from the second set. This shows that the current method is not extremely reliable and changes can be made to improve the experiment. An improvement to the method would be to always measure the volume of the sand used and smooth it down to the marked level on the side of the container. Sand that is not compacted may have a different result from compacted sand. This is because between the particles of non-compacted sand, there will be spaces of air. As the pendulum ball hits the surface of the sand, the kinetic energy will disperse into these spaces. Therefore, a smaller crater would be formed because the pendulum ball has less energy.
Validity of method:
The method is valid because it measures what is required to be measured in the experiment. The method described above was also followed step-by-step. The volume of the sand and height of the sand is unchanged. The pendulum ball remained unchanged throughout the course of the experiment as well. The vernier caliper measures the depth of the crater in centimeters and it is what the experiment is conducted for.
Reliability of results:
There are a total of 20 sets of data. The number of data collected makes the results reliable. Also, the average of the data from both sets of experiments were able to form a straight line graph with an outlier for 100.0cm at 1.77cm. Therefore, the results of this experiment is somewhat reliable.
Analysis
The graph is a straight line with increasing gradient. It shows that with an increase in height, the average depth of the crater also increases. The line graph does not pass through the origin (0,0) because the graph paper is too small to accommodate 10 sets of results (average of both sets of data).
Conclusion
The results of the experiment support the hypothesis. When the height at which the pendulum ball increases, the depth of the crater also increases. This is proven by the fact that the greater the distance between the ball and the ground, the greater the gravitational potential energy that the ball possesses. More gravitational potential energy is converted to more kinetic energy when the ball is dropped. As such, there is more energy to cause a greater damage to the ground, or in this case, sand, therefore resulting in an increase of depth of the crater.
Limitations and Improvements
