1.5 ANALYSING 1.5 ANALYSING SCIENTIFIC SCIENTIFIC

INVESTIGATIONINVESTIGATION

Observe the difference between the babies and the spring in diagram above. What physical quantities change from one situation to the other? How would you carry out an investigation to derive a conclusion relating the physical quantities involved?

Scientific Investigation procedure:

1) Making inference

- To interpret or explain what is being observed

- An early conclusion based on observation

2) Determining the variables

- A physical quantity which varies/changes during the course of a scientific investigation

- types of variable;

(a) Manipulated variable : is a physical quantity which is fixed before carrying out the experiment

(b) Responding variable : is a physical quantity that changes its value in response to the changes in

the manipulated variable

(c) Fixed variable : is a physical quantity that is set to remain constant throughout the experiment

3) Making a hypothesis

- it is about the relationship between the manipulated variable and responding variable when all other variables are kept constant

4) Planning the investigation

- determine the materials and apparatus together with the work procedure being followed/conducted

5) Conducting the investigation

- carry out the investigation according to the procedures planned

6) Collecting data

Eg:

Weight / W (N)Weight / W (N) Extension of spring/ x (cm)Extension of spring/ x (cm)

1.01.0

2.02.0

3.03.0

4.04.0

5.05.0

2.32.3

4.74.7

6.86.8

9.39.3

11.611.6

Data must be consistent (same unit and the same number of decimal places)

The row at the top of table must contain – name of the variable, symbol and unit for

measurement

7)Interpreting the data

- the data can be presented in form of bar chat,histogram,line graph,pie chart and so on.

- eg:

Extension/ x (cm)

Weight/ W (N)

In the graph that has been plotted:• x-axis represent the manipulated variables• y-axis represent the responding variables• both the axes must labeled with the correct symbol or the name of the quantity that is to be plotted

8) Making a conclusion

- A record that is made regarding an information that is being studied based on the aim of the experiment

- is made based on the shape of the graph that is plotted an also the value of the quantities obtained

through calculation using a formula

9) Making a complete report of an experiment

- the report should contain aim, hypothesis, variables, apparatus and material, procedure, result ,discussion and conclusion.

Refer to practical bookRefer to practical book

For more information how to plotted graphFor more information how to plotted graph

THE ENDTHE END

Essay Question:Essay Question:

(a)(a) Inference: Inference: A longer swing takes the longer time to complete one full A longer swing takes the longer time to complete one full oscillation. (Period of oscillation of a pendulum oscillation. (Period of oscillation of a pendulum depended depended on the length of the pendulum.)on the length of the pendulum.)

(b)(b) Hypothesis: Hypothesis: When length of the pendulum increases, its period of When length of the pendulum increases, its period of oscillation increases oscillation increases

(c)(c) (i) Aim: (i) Aim: To study the relationship between the length of pendulum To study the relationship between the length of pendulum and the period of oscillation of the pendulumand the period of oscillation of the pendulum

(ii) MV: length of pendulum(ii) MV: length of pendulum RV: period of oscillationRV: period of oscillation FV: mass of pendulum bobFV: mass of pendulum bob

(iii) Apparatus and material:(iii) Apparatus and material:

pendulum bob, thread, metre rule, retort stand, digital stop pendulum bob, thread, metre rule, retort stand, digital stop watch, coinwatch, coin

(iv) Arrangement of the apparatus(iv) Arrangement of the apparatus

(v)(v)Procedure:Procedure:

- Controlling the manipulated variable- Controlling the manipulated variable

A 10g pendulum bob is tied to end of a 10 cm length A 10g pendulum bob is tied to end of a 10 cm length thread. The length, thread. The length, ll of pendulum is measured from of pendulum is measured from

the the end below the small coin to the centre of the bobend below the small coin to the centre of the bob

- Responding variable- Responding variable

The time,t taken to complete 20 full oscillation is The time,t taken to complete 20 full oscillation is recorded recorded with stop-watch. The period of one complete with stop-watch. The period of one complete oscillation, T oscillation, T is calculated as T= t/20is calculated as T= t/20

- the experiment procedure is repeated by taking the length of - the experiment procedure is repeated by taking the length of the pendulum to be the pendulum to be ll = 20cm, 30cm, 40cm, 50 cm and 60 cm. = 20cm, 30cm, 40cm, 50 cm and 60 cm.

(vi)(vi) Tabulate dataTabulate data

Length of Length of pendulum,pendulum,ll(cm)(cm)

Time for 20 oscillation, t (s)Time for 20 oscillation, t (s) Period, Period, T(s)T(s)11 22 averageaverage

10.010.0

20.020.0

30.030.0

40.040.0

50.050.0

60.060.0

(vii) Analyse data(vii) Analyse data

A graph of TA graph of T22 against against ll is sketch. is sketch.

T2 (s2)

l (cm)

Now, try to answer question no 2 Now, try to answer question no 2 on page 9on page 9