Base Units+Uncertainty

Which of the following is NOT true about uncertainties?

• Uncertainties are the same as errors

• Uncertainties are not the same as errors

• Uncertainties are an estimate

• Uncertainties represent a range of values around a measurement

If the length of a box is measured multiple times as 12.55 cm, 12.45 cm, and 12.51 cm, what is the uncertainty of the measurement?

• 0.05 cm

• 0.10 cm

• 0.01 cm

• 0.15 cm

Write the formula for percentage uncertainty.

• percentage uncertainty = (absolute uncertainty / measured value) × 100%

• percentage uncertainty = (measured value / absolute uncertainty) × 100%

• percentage uncertainty = (absolute uncertainty × measured value) × 100%

• percentage uncertainty = (measured value - absolute uncertainty) × 100%

How do you find the uncertainty in a reading from a voltmeter?

• ± half the smallest division

• ± the largest division

• ± the average of all readings

• ± twice the smallest division

How do you find the uncertainty in a measurement of length from a ruler?

• at least ±1 smallest division

• exactly ±0.1 mm

• always ±5 cm

• no uncertainty at all

How do you find the uncertainty in repeated data?

• half the range i.e. ± ½ (largest - smallest value)

• the mean of all values

• the sum of all values divided by the number of trials

• the difference between the first and last value

When adding or subtracting two values with uncertainties, what should you do with the absolute uncertainties?

• Add the absolute uncertainties.

• Multiply the absolute uncertainties.

• Subtract the absolute uncertainties.

• Ignore the absolute uncertainties.

Given the diameter of a tyre (d₁) = 55.0 ± 0.5 cm and the diameter of the inner tyre (d₂) = 21.0 ± 0.5 cm, calculate the difference in diameters (d₁ - d₂).

• 34.0 cm

• 36.0 cm

• 32.0 cm

• 30.0 cm

Given the uncertainties in the diameters: d₁ = 55.0 ± 0.5 cm and d₂ = 21.0 ± 0.5 cm, what is the uncertainty in the difference (d₁ - d₂)?

• ± 0.5 cm

• ± 2 cm

• ± 1.0 cm

• ± 1 cm

When multiplying or dividing measurements with uncertainties, what should you do with their fractional or percentage uncertainties?

• Add them

• Subtract them

• Multiply them

• Ignore them