Page 48 - Physics

Physics for Secondary Schools

There are two types of stopwatches, namely Acti vity 2.4
analogue stopwatch and digital stopwatch as shown
in Figure 2.20. Aim: To determine
the period of
a simple
pendulum.

Materials: String, retort
stand, analogue
or digital
stopwatch and
object (200 g)

(a) Analogue stopwatch (b) Digital stopwatch Procedure

Figure 2.20: Stopwatches 1. With the guidance of your
teacher, construct a simple
An analogue stopwatch has two scales, the minute pendulum by tying one end
scale and the second scale. The pointer on each of the string to the retort
scale enables the time that has elapsed to be read, stand.
see Figure 2.20 (a). 2. Tie the 200 g object on the
other end of the string.
A digital stopwatch shown in Figure 2.20 (b) 3. Pull the object slightly to
displays the actual time in minutes and seconds. one side and release so that
Digital stopwatches are more accurate than it swings back and forth.
analogue stopwatches. A large digital version of 4. Using a stopwatch, measure
a stopwatch is called a stop clock. Stop clocks are the time for the pendulum
designed for distant viewing as in sports stadiums. to swing back and forth ten

How to operate a stopwatch times.

The timing functions of a stopwatch are controlled 5. Record your observations.
by two buttons, one at the top of the watch and 6. Calculate the period
the other at the side of the watch. Pressing the top (time for one complete
button starts the timer and pressing it again stops oscillation).
the timer. The elapsed time is then displayed on the 7. Record your results.
screen. The side button usually has two functions, 8. Repeat steps 4-7 four times.
fi rst, to reset the stopwatch to zero and second Question
function to record the split times or lap times. When How could you obtain the
it is pressed while the stopwatch is running, the period (T) of the simple
elapsed time is displayed, while the watch keeps pendulum?
on recording the time elapsed.

42
Student’s Book Form One

Physics Form 1 Final.indd 42 16/10/2024 20:55