Measurements Flashcards
What is mass?
The amount of matter in an object.
What are the SI units of mass?
Kilograms (Kg) and grams (g).
What are the two main apparatus used to measure mass?
Beam balance and digital balance.
What is the function of a beam balance?
To compare masses.
What precaution should be taken when using a beam balance?
Place it on a horizontal (flat) surface.
What is another name for a digital balance?
Sensitive balance, top-pan balance, or electric balance.
What are two precautions when using a digital balance?
- Place it on a horizontal surface
- Check for zero error.
What is length?
The distance between two points.
What are the SI units of length?
Meters (m), kilometers (Km), centimeters (cm), and millimeters (mm).
What are three common apparatus used to measure length?
Meter ruler, measuring tape, micrometer.
What is a meter ruler used for?
To measure up to 1 meter.
What is a measuring tape used for?
To measure lengths greater than 1 meter.
What is a micrometer used for?
To measure very small lengths (less than 1 cm), such as the thickness of wire or paper.
How do you accurately measure the thickness of a sheet of paper?
- Check the zero reading of a micrometer.
- Measure the thickness of 20 sheets of paper.
- Divide the thickness recorded by 20.
- Repeat and take the average of results.
Extra:
* Use identical sheets of paper.
* Avoid parallax error by looking perpendicularly.
How do you measure the length of a non-curved object?
Use a ruler: End length – Starting length.
How do you measure the length of a curved object?
- Place the object between two wooden blocks or set squares.
- Use a ruler: End length – Starting length.
How do you measure the inner diameter of a ring?
Calculate the total length of the ring using a ruler.
Subtract the inner thickness of both sides of the ring.
What is time?
The measurement of the duration of an event.
What are the SI units of time?
Seconds (s), minutes (min), hours (h) (convert all to seconds).
What are two apparatus used to measure time?
Stopwatch and clock.
How do you measure the period of a pendulum?
- Use a pendulum and stopwatch.
- Check the zero reading of the stopwatch.
- Start the stopwatch when releasing the pendulum.
- Count 20 oscillations and record the time.
- Divide the total time by 20 to get the period of one oscillation.
- Repeat and take the average.
What are precautions in the pendulum experiment?
- Check for zero error.
- Don’t count too many oscillations to avoid loss of count.
What are two sources of error in the pendulum experiment?
- Human error: reaction time.
- Instrument error: zero error, battery empty.
What is volume?
The space occupied by matter.
What are the SI units of volume?
Cubic centimeters (cm³), cubic millimeters (mm³), cubic meters (m³).
How do you convert volume units?
The same as length but raised to the power of 3
cm³ to m³ (x 100^3)
What is the formula for the volume of a cube or cuboid?
L × W × H.
What is the formula for the volume of a cylinder?
πr²h.
What is the formula for the volume of a sphere?
4πr³/3.
How do you measure the volume of an irregular object?
Using the displacement method.
What apparatus are used in the displacement method?
Measuring cylinder, water, object, sinker (if needed).
Describe the steps of the displacement method.
- Add sufficient water to the measuring cylinder and record volume as V1.
- Submerge the object and record new volume as V2.
- Subtract V1 from V2 (V2 - V1) to get the volume of the object.
What are three precautions when using the displacement method?
- Avoid parallax error.
- Ensure the object is fully submerged.
- Use a sinker if the object is less dense than water.
What is density?
The mass per unit volume of a substance.
What is the formula for density?
Density = Mass / Volume (D = m/v).
What are the SI units of density?
Kilograms per cubic meter (Kg/m³) or grams per cubic centimeter (g/cm³).
How do you find the density of an object?
- Measure the mass using a digital balance.
- Measure the volume using the displacement method.
- Divide mass by volume (D = m/v).
What is the difference between accuracy and precision in measurements?
Accuracy refers to how close a measurement is to the true or accepted value, while precision describes the consistency or repeatability of multiple measurements.
How do significant figures and uncertainties affect the reporting of measurements?
significant figures reflect the digits in a measurement that are known reliably, and uncertainties indicate the possible error range; both are crucial for expressing the reliability and exactness of data.
What distinguishes systematic errors from random errors in experiments?
Systematic errors are consistent, repeatable mistakes (e.g., calibration issues) that skew all measurements in one direction, whereas random errors vary unpredictably and can be reduced by taking multiple measurements and averaging.
Why is regular instrument calibration important in experimental measurements?
Calibration ensures that instruments are providing accurate readings by correcting zero errors and other deviations, which is essential for maintaining measurement reliability.
