ib physics design lab

Aim- To investigate the effect of varying  drop height to the time it takes for a ball to come to rest.

 Hypothesis- The higher the ball is dropped the longer it will take to stop bouncing. ( Distance∝Time)

Independent variable – Height at which the ball is dropped ( measured in cm)

Dependent Variable – Time ( measured in seconds)

Controlled variable – Mass of the ball, surface at which the ball strikes, temperature.

Apparatus needed

• Clamp stand

Centimeter scale

Rubber ball

Stop watch

Method

• Set up the apparatus as shown in the diagram

Make sure the ruler is straight i.e. parallel to the clamp and perpendicular to the surface.

Mark the distance at which the ball is to be dropped ( in this experiment I have started from 10cm) and record it

Drop the ball and start the stopwatch simultaneously.

Stop the watch until the ball stops  bouncing completely

Record the data ( the height at 10cm and it's correspondent time)

Repeat this process two more times ( with the same height – the average will be considered to avoid random errors)

Use the same process with varying heights ( 10, 20 , 30...) and make sure that for each height there are three separate readings.

•  Calculate the average time  for each heights using this formula - ( T1+T2+T3)   = T  

                                                                                                                            3

Data Collected 

Time Uncertainty

Using the following equation The uncertainty of time is found for each value of Height.

 Uncertainty of time = ( Tmax-Tmin)/2

From my calculation the greatest uncertainty was found when height was  _10 cm therefore this is my uncertainty.

(3.30-2.85)/2 = 0.225

Height Uncertainty

The smallest increment in the centimeter scale is 1mm or one tenth of a centimeter therefore I estimated to the hundredths i.e.   0.1

The gradient of the graphs  is 0.0506 s/cm

It is a linear and proportional and all  the data points lie on the best straight line.

 Conclusion and Evaluation

According to the graph the the increased height do result longer time that made the ball come to complete stop. It was because of the increased  energy each time the ball hit the surface and bounced back.

I think the procedure mentioned is capable of bringing out an accurate result. There was not any anomalies present in the graph. The procedure/method  also quite easy to carry out.

However I did not use metal clamps to hold the ruler straight, instead I taped it against the wall. I could not put all three lines in the same graph too. Which shows with the better use of technology the accuracy rate could have gotten higher.

Improvements

• More repeats  could be carried out

Better use of the Graphical analysis software , I could not get three line in a single graph

Parallax errors could have been avoided if there was another person to help

The temperature was not exactly constant

For better accuracy a sensor or a video camera could have been used to record the number of bounces.