Exam-style Questions: Units, Quantities and Measurements

  1. Here is a list of five units for physical quantites.

    kgm-3

    Nm-2

    Cs-1

    Ω m

    Ws

    From the list

    a) write down the unit for electrical current ................

    b) write down the unit for mechanical stress ................

    (2 Marks)

    (Marks available: 2)

    Answer

    Answer outline and marking scheme for question: 1

    a) Cs-1

    b) N m-2

    (2 Marks)

    (Marks available: 2)

  2. Here is a list of five units

    J

    N

    Jkg-2

    Nkg-1

    From the list write down the correct unit for

    a) the energy stored in a stretched spring ................

    b) centripetal force ................

    (Marks available: 2)

    Answer

    Answer outline and marking scheme for question: 2

    a) the energy stored in a stretched spring .............J...

    b) centripetal force .........N.......

    (Marks available: 2)

  3. The acceleration, a, of a body in simple harmonic motion is given by:

    a = - (2πf)2x

    Where f if frequency of the oscillation and x is the displacement.

    Show that the right hand side of the equation has the units of acceleration.

    (Marks available: 2)

    Answer

    Answer outline and marking scheme for question: 3

    Unit of f 2 is s-2 (1 Mark) or f is s-1 (unit of x is m therefore)

    combined unit is m s-2 (which is the uni of acceleration) (1 Marks)

    (Marks available: 2 Marks)