Chapter 1

Errors in measurement may be either systematic or random.

Which of the following involves random error?

• not allowing for zero error on a moving coil voltmeter

• not subtracting background count rate when determining the count rate from a radioactive source

• stopping a stopwatch at the end of a race

• using the value of g as 10 N kg^-1 when calculating the weight from mass

Which of the following is a unit of pressure?

• kg m s^-1

• kg m^-1 s^-2

• kg m² s^-2

• kg m^-2 s^-1

• 327.7 m s^-1

• 328 m s^-1

• 330 m s^-1

• 300 m s^-1

Answer explanation

Value of error = 327.66 x 3%

= 9.83 m s^-1

= 10 m s^-1

Speed of sound = 330 m s^-1 (rounded off)

• 2 %

• 4 %

• 6 %

• 8 %

A metal sphere of radius r is dropped into a tank of water. As it sinks at speed v, it experiences a drag force F given by F = krv, where k is a constant.

What are the SI units of k?

• kg m² s^-1

• kg m^-2 s^-2

• kg m^-1 s^-1

• kg m s^-2

• 1 %

• 4 %

• 7 %

• 8 %

• 11 %