Physical Quantities and Measurements 1

Which definition is correct and uses only quantities rather than units?

• Density is mass per cubic metre.

• Potential energy is energy per unit current.

• Pressure is force per unit area.

• Speed is distance travelled per second.

For which quantity is the magnitude a reasonable estimate?

• frequency of a radio wave 500 pHz

• mass of an atom 500 µg

• the Young modulus of a metal 500 kPa

• wavelength of green light 500 nm

Which pair of quantities contains one vector and one scalar quantity?

• displacement; force

• kinetic energy; power

• acceleration; momentum

• velocity; distance

The diameter of a cylindrical metal rod is measured using a micrometer screw gauge. The diagram below shows an enlargement of the scale on the micrometer screw gauge when taking the measurement.

What is the cross-sectional area of the rod?

• 3.81 mm2

• 11.4 mm2

• 22.8 mm2

• 45.6 mm2

Which pair of units contains one derived unit and one SI base unit?

• ampere coulomb

• kilogram kelvin

• metre second

• newton pascal

What is equivalent to 2000 microvolts?

• $2\ \mu JC^{-1}$

• 2 mV

• 2 pV

• 2000 mV

Which product-pair of metric prefixes has the greatest magnitude?

• pico × mega

• nano × kilo

• micro × giga

• milli × tera

A calibration graph is produced for a faulty ammeter.

Which ammeter reading will be nearest to the correct value?

• 0.2 A

• 0.4 A

• 0.6 A

• 0.8 A

A fixed quantity x0 is measured many times in an experiment that has experimental uncertainty. A graph is plotted to show the number n of times that a particular value x is obtained. Which graph could be obtained if the measurement of x0 has a large systematic error but a small random error?

• 
• 
• 
• 

Which list contains only scalar quantities?

• area, length, displacement

• kinetic energy, speed, power

• potential energy, momentum, time

• velocity, distance, temperature