## Experiments in Physics

Sep 04, 2012
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Measurements and Units

Activity 1
MEASUREMENT

I. OBJECTIVE:
To be able to measure lengths, area, volume and  mass of different solids of different shapes using different measuring tools with accuracy

II. MATERIALS
meter stick / ruler  rectangular wooden block
vernier caliper   irregular shaped marble cuttings
balance           solid sphere (marble balls)
water    hollow cylinder (tin cans)

III. THEORY
Measurement or mensuration is an act or process of determining dimension, capacity or an amount of something. In science the System International (SI) of measurement is used

The three basic measurable quantities are length, mass and time.  .  The SI is using the metric system where the meter is the standard unit for length, kilogram for mass and second for time, or the MKS system.  Smaller units are also used, that is, centimeter, gram, and second, or the CGS system.   The units in the metric system follows the decimal system of counting, that is, by tens. Greek prefixes are used to indicate the place value of the given measurement.

Other dimensions derived from the basic ones are area, volume, density, work, speed, force, acceleration, power, and many others.
Mass Density of solids =  Mass / Volume
Weight Density = Weight / Volume

How to use and read a vernier caliper

An ordinary vernier caliper has jaws you can place around an object, and on the other side jaws made to fit inside an object. These secondary jaws are for measuring the inside diameter of an object. Also, a stiff bar extends from the caliper as you open it that can be used to measure depth.
The basic steps are as follows:

1. Preparation to take the measurement, loosen the locking screw and move the slider to check if the vernier scale works properly. Before measuring, do make sure the caliper reads 0 when fully closed. If the reading is not 0, adjust the caliper’s jaws until you get a 0 reading. If you can’t adjust the caliper, you will have to remember to add to subtract the correct offset from your final reading. Clean the measuring surfaces of both vernier caliper and the object, then you can take the measurement.
2. Close the jaws lightly on the item which you want to measure. If you are measuring something round, be sure the axis of the part is perpendicular to the caliper. Namely, make sure you are measuring the full diameter. An ordinary caliper has jaws you can place around an object, and on the other side jaws made to fit inside an object. These secondary jaws are for measuring the inside diameter of an object. Also, a stiff bar extends from the caliper as you open it that can be used to measure depth.
3. How to read the measured value:

1), Read the centimeter mark on the fixed scale to the left of the 0-mark on the vernier scale. (10mm on the fixed caliper)
3). Look along the ten marks on the vernier scale and the millimeter marks on the adjacent fixed scale, until you find the two that most nearly line up. (0.25mm on the vernier scale)

IV. PROCEDURE

A. Wooden Block
1. Measure the length, width and height of the wooden block using the ruler and the vernier
caliper.    Compute the area and the volume.  Record all the results in Table 1.1
2. Make 3 trials
3. Compute the average volume using the ruler and using the caliper.

B.  One-Peso Coin
1.  Measure the diameter of a one-peso coin using the ruler and the vernier
caliper.  Compute for the radius and surface area of the coin.  Record all the results in Table  1.2
2. Make 3 trials another one-peso coin.
3. Compute the average surface area using the ruler and using the caliper.   C

C Spherical Marble
1.  Measure the diameter of spherical marble using the ruler and the vernier
caliper.  Compute for the radius, surface area and volume of the marble.  Record all the
results in Table  1.3
2. Make 3 trials
3. Compute the average volume using the ruler and using the caliper.

D. A Sheet of Paper
1.  Measure the thickness of 30 sheets of a book using the ruler and the vernier caliper.
Compute for the average thickness of each sheet by dividing the thickness by the number of
sheets.  Record all the results in Table  1.4
2.   Make 2 more trials with 60 and 90 sheets
3.   Compute the average thickness using the ruler and using the caliper.

E. Irregular-shaped solids- cut out marble
1. Get the mass of the stone.
2. Place water in a graduated cylinder and get the initial volume, Vo, of water.
3. Drop the stone into the cylinder and get the final volume, V, of the water
4. Compute for the volume of the stone by getting the difference R - Ro
Record all the results in Table  1.4
5.     Compute for the mass density of the stone
6.   Make 3  trials using the same kind of stone but with different mass.
7.  Get the average mass density.
8.  Compute  for the percentage error of the mass density

E = (experimental  - accepted) /  accepted x  100%

Mass density of marble (accepted value) = 2.5 gm/cc

V. RESULTS

Table 1.1  Wooden Block
Trials Length (cm) Width (cm) Surface Area (cm2) Volume (cm3)
ruler caliper ruler caliper ruler caliper ruler caliper
1
2
3

Average volume using ruler:  ______________________
Average volume using caliper: _____________________
Percentage Error: ________________________________

Table 1.2  One-Peso Coin
Trials diameter (cm) radius (cm) Surface Area (cm2)
ruler Caliper ruler caliper ruler caliper
1
2
3

Average surface area using ruler:  ______________________
Average surface area using caliper: _____________________
Percentage Error: ________________________________
Table 1.3  Spherical Marble
Trials      diameter (cm) radius (cm) Surface Area (cm2) Volume (cm3)
ruler caliper ruler caliper ruler caliper ruler caliper
1
2
3

Average volume using ruler:  ______________________
Average volume using caliper: _____________________
Percentage Error: ________________________________

Table 1.4  A Sheet of Paper
No. of Sheets Thickness   (cm) Ave Thickness (cm)
ruler caliper          ruler caliper
30
60
90

Average thickness using ruler:  ______________________
Average thickness using caliper: _____________________
Percentage Error: ________________________________

Table 1.5 Irregular Solids- Marble cuttings
Trials Mass (gram) Vo (cc)
(water only) V (cc)
(water + marble) Volume of the Marble  (cc) Mass Density
(gm/cc)
1
2
3

Average density (experimental):  ______________________
Accepted density value: _____________________
Percentage Error: ________________________________

VI. Questions:
1. What measuring instrument can measure more accurately bigger lengths?
2. What measuring instrument can measure more accurately smaller lengths?
3. Can the method used to measure the volume and density of irregular-shaped solids can also be applied to the regular-shaped solids?
4. Describe a method on how to measure the thickness of a strand of hair.

VII. Conclusion:

VIII. Sample Computations

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Measurement, Vectors, Force and Motion, Friction, Equilibrium, Free-Fall, Projectile, Momentum, Hooke's Law, Energy and Theormodynamics