Physics Lab Test 1 (2048L)

Which type of scientist or engineer primarily performs measurements?

Experimentalist

Accuracy refers to how:

Close a measurement is to the true value

Precision refers to how:

Repeatable measurements are

Which situation is most desirable in scientific measurement?

High accuracy, high precision

Why is determining accuracy difficult?

The true value is often unknown

A measurement device with smaller divisions generally provides:

Higher precision

According to the lecture, when using a ruler, measurements should be reported:

Only to the precision allowed by the smallest tick mark

The uncertainty of a measuring device is typically taken as:

One

If the smallest division on a ruler is 1 mm, the uncertainty is:

±0.5 mm

Error bars on a graph represent:

Measurement uncertainty

Which statement about the actual (or true) value is most consistent with error analysis?

It should lie within the uncertainty range.

How many significant digits are in the number 2.00?

3

How many significant digits are in the number 0.10?

2

In the number 1.01, the zero is:

Significant because it is between nonzero digits

Why is the number 100 considered ambiguous in significant digits?

The trailing zeros may or may not be significant

Why are all scientific measurements subject to uncertainty?

No measurement can be 100% accurate

In this course, what term is used for the uncertainty associated with a measurement?

Absolute uncertainty

For an analog instrument, the uncertainty is typically:

Half of the smallest possible measurement

For a digital instrument, the uncertainty is usually:

Equal to the smallest displayed increment

A digital stopwatch reads to 0.01 s, but human reaction time is about 0.2 s. Which source of uncertainty is more important?

Human reaction time

Why might the last digit on a stopwatch be meaningless in some experiments?

Human reaction error is larger than the instrument precision

Fractional uncertainty is defined as:

Uncertainty ÷ measurement

Percentage uncertainty is obtained by:

Multiplying fractional uncertainty by 100%

Measuring a large object with the same ruler generally produces:

Smaller percentage uncertainty

Which measurement would typically have the larger percentage uncertainty if the same ruler is used?

Diameter of a pencil (4 mm)

When adding or subtracting measured quantities, uncertainties are propagated by:

Adding absolute uncertainties

Which statement is true when subtracting two measurements?

Absolute uncertainties are still added

When multiplying or dividing measured quantities, the first step in uncertainty propagation is to determine:

Fractional uncertainty of each measurement

For multiplication and division, uncertainties are propagated by:

Adding fractional uncertainties

A student's speed is calculated from distance divided by time. To find the uncertainty in speed, the fractional uncertainties of distance and time should be:

Added

After finding the combined fractional uncertainty of a calculated quantity, the propagated absolute uncertainty is found by:

Multiplying by the best value

Several measurements of the same quantity can be presented in a table. If the random uncertainty of the several measurements is larger than the instrument uncertainty, the absolute uncertainty of the measurement set should be taken from the:

Random uncertainty

Several measurements of the same quantity can be presented in a table. If the random uncertainty of the several measurements is smaller than the instrument uncertainty, the absolute uncertainty of the measurement set should be taken from the:

Instrument uncertainty

For repeated measurements presented in a table, the random uncertainty is estimated as:

The largest deviation from the average

A data set shows measurements clustered very closely together, but the average differs from the true value. This situation is:

High precision, low accuracy

Which type of error causes measurements to consistently differ from the true value in the same direction?

Systematic error

Why is systematic error difficult to identify?

The true value is usually unknown.

In many experiments, the random uncertainty obtained from repeated measurements is:

Often larger than instrument uncertainty

According to the lecture, a powerful way to detect systematic error is by:

Analyzing the graph and trendlines of min and max slopes

For many physical relationships discussed in the lecture, the ideal trendline should:

Pass through the origin

Why are minimum and maximum gradient lines added to a graph?

To estimate uncertainty in the slope

The minimum and maximum gradient lines are usually drawn using:

The first and last data points, if not outliers

The best estimate of the slope is obtained from:

The average of the maximum and minimum gradients

The uncertainty in the slope is calculated from:

(max slope − min slope)/2

Which of the following is a characteristic of a good graph?

A suitable scale should be chosen

What information should always be included on graph axes?

Quantity names and units