Page 20 - Physics
P. 20
Physics for Secondary Schools
Answer: variable is the time it takes for the
Hypothesis; If a solar eclipse occurs, pendulum bob to complete a given
then there will be a decrease in number of oscillations.
temperature compared to normal (b) Independent variable; A variable
conditions, due to the obstruction of
the sun’s radiation towards the Earth’s which does not change even when the
surface. experimental condition is changed. For
example, the length of the pendulum
bob is independent variable.
Task 1.3
(c) Controlled variable; This is a variable
You notice that some metal objects left that is kept constant during an
outside during a cold night feel much experiment. For example, the number
colder to the touch than other objects of oscillations is a controlled variable.
made of wood or plastic. Propose a
testable hypothesis to explain this Designing Physics experiments
observation.
Designing an experiment involves creating
a set of procedures to systematically
Fact test a hypothesis. This requires a strong
In science we never prove a hypothesis understanding of the system under study.
through a single experiment because
there is a chance that you made an error For valid conclusions, the selection of a
somewhere along the way. What you can representative sample and controlling
say is that, your results support or do not any extraneous variables is important. To
support the original hypothesis. experiment, we need fi rst to understand
how to identify the experimental
3. Conducting an experiment variables. The following examples will
help you to build skills on how to identify
Scientists particularly physicists
experiments to study the causal the variables that need to be manipulated.
relationships. This is done by manipulating
one or more independent variables and Example 1.5
measuring their effects on one or more A student is investigating how the
dependent variables. There are three height of a ramp affects the distance
different types of variables, namely; a toy car travels. The student changes
dependent, independent, and controlled the height of the ramp and measures
variables. the distance the car travels as shown
(a) Dependent variable; A variable which in Figure 1.19. Identify the dependent,
changes if the experimental condition independent, and controlled variables
changes. For example, the dependent in this experiment.
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Student’s Book Form One
Physics Form 1 Final.indd 14 16/10/2024 20:55
