Topic 1.3 Error and Uncertainty

• A

• B

• C

• D

The diagram shows a micrometer scale

• 5.64 mm

• 7.14 mm

• 7.16 mm

• 7.64 mm

Accuracy means

• the measurements are close to each other

• the measurement is close to the true value

• the measurements are close to each other

• the measurements are close to each other and the true value.

What does the graph represents?

• small systematic error, small random error

• small systematic error, large random error

• large systematic error, small random error

• large systematic error, large random error

A fixed quantity x_o is measured many times in an experiment that has experimental uncertainty.

• precise and accurate

• precise but not accurate

• not precise but accurate

• not precise and not accurate

Which result is not accurate but precise?

• A

• B

• C

• D

A quantity x is to be determined from the equation

x = P – Q

P is measured as 1.27 ±0.02 m

Q is measured as 0.83 ±0.01 m

What is the percentage uncertainty in x to one significant figure?

• 0.4%

• 2%

• 3%

• 7%

The velocity of a liquid in a pipe can be calculated by measuring the force on a small disc placed in the centre of a pipe with its plane perpendicular to the flow. The equation relating the force to the velocity is

force = constant x (velocity)²

If the velocity is to be found with a maximum uncertainty of 1%, what is the maximum permissible uncertainty measuring the force?

• 0.5%

• 1%

• 2%

• 4%

The frequency of oscillation f of a mass m suspended from a vertical spring is given by 

 $f=\frac{1}{2\pi}\sqrt{\frac{k}{m}}$  
where k is a constant.  Which one of the following plots would produce a straight-line graph?

• f against m

•  $f^2$    against 1/m 

• f against  $\sqrt{m}$  

• 1/f against m

When performing an experiment, a student should minimise the uncertainty of any measurement.

In which case is the student reducing the systematic error in a measurement?

• adjusting a voltmeter needle pointer to the zero position before using it to measure a potential difference

• measuring the diameter of a wire at several points and orientations

• measuring the mass of 100 paperclips to determine the mass of one paperclip

• timing 20 oscillations of a mass on a spring to determine the period of one oscillation