Physical Quantities and Units

The equation relating pressure and density is p = ρgh.

How can both sides of this equation be written in terms of base units?

• [N m^-1 ] = [kg m^-3 ] [m s^-1 ] [m]

• [N m^-2 ] = [kg m^-3 ] [m s^-2 ] [m]

• [kg m^-1 s^-2] = [kg m^-3 ] [m s^-2 ] [m]

• [kg m^-1 s^-1] = [kg m^-1 ] [m s^-2 ] [m]

What is a reasonable estimate of the diameter of an alpha particle?

• 10^-15 m

• 10^-12 m

• 10^-9 m

• 10^-6 m

A laser emits light of wavelength 600 nm.

What is the distance, expressed as a number of wavelengths, travelled by the light in one second?

• 5 x 10⁸

• 5 x 10¹¹

• 5 x 10¹⁴

• 5 x 10¹⁷

At temperatures close to 0 K, the specific heat capacity c of a particular solid is given by c = bT ³, where T is the thermodynamic temperature and b is a constant characteristic of the solid.

What are the units of constant b, expressed in SI base units?

• m² s^-2 K^-3

• m² s^-2 K^-4

• kg m² s^-2 K^-3

• kg m² s^-2 K^-4

The drag force F acting on a moving sphere obeys an equation of the form F = kAv², where A represents the sphere’s frontal area and v represents its speed.

What are the base units of the constant k ?

• kg m⁵ s^-4

• kg m^-2 s^-1

• kg m^-3

• kg m^-4 s²