- Release mechanism
- Plumb bob
-trip plate
Procedure:
- A steel ball was inserted between the jaws of the release mechanism
- The height was adjusted to 1 meter and half a meter, measured from the bottom of the ball to the trip plate
- The plumb bob was used to locate the centre of the trip plate , to ensure that the ball falls on it and to make sure the release mechanism is perpendicular to the surface of the plate
- a circuit was made between the release mechanism, the trip plate and the electronic timer. it was configured to start counting as soon as the ball is released and to stop counting when it touched the plate
- The timer was switched on and RESET was pressed
- the thumbscrew was pressed to release the ball, it was held straight rather than curved to achieve better results
- when the ball hits the plate, the spring comes up and the timer stops
- the time was measured
- The distance ( independent variable) was varied by moving the clamp upwards or downwards until the distance from the bottom of the ball equals 0.5 m or 1 m
- The time was read from the electronic timing device
- The same steel ball was used through out the experiment and the plumb bob was kept in the same length through out the trials
- for each length 20 trials were performed and averaged
- the distance the ball travels was measured after every trial
Data Collection:
Table 1. The time it takes the ball to fall 1 meter
Table 2. The time it takes the ball to fall half a meter
Data
Processing and presentation:
Average Time in table 1 = Sum/20
= 9.049/20
0.452 ± 0.006
s = ½ g t^2
1 = ½ g (0.452)^2
1/g = (0.452^2)/2
G= 2/(0.452^2)
G=9.79 ± 0.4
Average Time in Table 2 = Sum/20
= 6.331/20
0.317 ± 0.006
s = ½ g t^2
½ = ½ g (0.317) ^2
(1/2) / (1/2) = g (0.317)^2
1 = g (0.317)^2
g = 1 / (0.317)^2
G = 9.95 ± 0.4
- Percentage uncertainty of gravity 1 = (0.4/9.79) x 100 = 4.09%
- Percentage uncertainty of gravity 2= (0.4/9.95)x100 = 4.02%
Conclusion:
- The results were in the same range
- The firs gravity was very close to the ideal gravity
Evaluation:
- The method used was fairly accurate
-but there are many sources of error which may affect the result obtained using it
- Sources of Error:
- Air resistance is an error, but it has a slight effect
- The thumbscrew is clicked twice
- The thumbscrew wasn’t pressed properly
- The ball might not fall in the centre
- The clamp may move slightly upwards or downward after every few measurements
- The same person should press the thumbscrew through out all the experiment
- The thumbscrew should be pushed with quickly and firmly
