Physics 311, Quiz #11

Question 1: The SI units of momentum are ...

1. kg * m^2 / s
2. m * kg / s^2
3. kg * m / s

    Answer:  b,  kg * m / s

Question 2: Momentum is a

1. scalar
2. vector

    Answer:  b, vector  (it has the same direction as its velocity component)

Question 3: If the net external forces on an object are zero, then its momentum must be

1. zero
2. constant
3. neither

    Answer:  constant.  The time derivative of momentum is force:

                   dp
                  ----  =   external forces
                   dt

             So if the external forces are zero, then the CHANGE in
             momentum with time must be zero; hence, momentum must
             be a constant

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