Page 50 - Physics

Physics for Secondary Schools

the fi xed mark at the right of the balance. 5. To fi nd the mass of the object on the
If the pointer is not straight, use the counter pan, add the numbers from the three
weight to adjust as needed. beams. That is,
0 g 20 g 5 g+ + = 25 g.

Example 2.5
The diagram in Figure 2.24 shows
the position of the three weights on
Figure 2.22: A set triple balance the beams of a triple beam balance.
Determine the mass of the object.
1. Once the balance has been adjusted,
place the object to be measured on the
pan.
2. Move the 100 gram weight to the right
along its beam until the indicator just Figure 2.24
drops below the fi xed mark. The mark to Solution
the immediate left of this point indicates Start with 100 g, 10 g, then 1 g. That is,
the number of hundreds of grams. Note
down this value which is 0 g for the case 300 g 40 g 3.5 g 343.5 g.  
of Figure 2.23.
3. Move the 10 gram weight to the right A digital balance
along its beam until the indicator A digital balance is a very sensitive
drops below the fi xed mark. The mark weighing balance. It can measure masses
immediately to the left of this point to an accuracy of one thousandth of a gram
indicates the number of tens of grams. (0.001 g). The object whose mass is to be
Note down this value, 20 g for the case measured is placed on the pan on top of
of Figure 2.23. the balance and the mass read from the

4. Move the 1 gram weight to the right digital display.
along its beam until the pointer coincides
directly with the fi xed mark on the right, Task 2.6
as shown in Figure 2.23. Note down Perform the following tasks:
this value which is 5 g and given to the
nearest tenth of a gram. 1. Use a triple beam balance to measure
the mass of your physics textbook,
exercise book and your pen.
2. Use a digital balance to measure the
mass of the same materials.
3. Compare the two measurements and
Figure 2.23: The three weights showing the discuss any differences.
mass of the object

44
Student’s Book Form One

Physics Form 1 Final.indd 44 16/10/2024 20:55