One dimensional motion describes the changes in the position of
an object over time in terms of its displacement, velocity, and
acceleration in one direction. The motion in that
direction is independent of the displacement, velocity, and
acceleration associated with any of the perpendicular directions.
For example, the acceleration due to gravity near the surface of
the earth has a value of 9.8 m/s2, downward. This
affects the vertical motion of an object but has no effect on the
motion of the object in either of the horizontal directions. Thus,
one-dimensional motion forms the foundation of our understanding of
general motion in three dimensions.
Instructions for this activity:
For our discussion, you will address one of three slightly
different versions of the case of a ball falling to the base of a
50.0 m tall building.
Neglect air resistance.
The magnitude of the acceleration is 9.80 m/s2.
The eventual position of the ball is at the base of the
building, 50.0 m below this initial position.
Upward is defined as positive. Displacements, velocities and
accelerations directed upwards are positive. Conversely, if
directed downwards, these same quantities are negative. Thus, the
base of the building is located at -50.0 m, and acceleration is
-9.80 m/s2.
For the Case you are assigned, answer the following
questions. Support your answer with any necessary
calculations.
How long does the ball take to reach the base of the
building?
What is the final velocity of the ball just before striking the
ground?
Answer the additional questions for your Case as specified in
the table below.
Freefall Case 1: Near the edge of the building the ball is
thrown upward with an initial velocity of 14.7 m/s, at time t =
0.00 s.
Additional question: If downward were to have been chosen
as the positive direction, how would this affect the values of
displacement, velocity, and acceleration given in the description
of the case study? Comment on the dependence of physical results,
if any, on the choice of the positive direction chosen by
observers.