Question

A Student throws a ball vertically downward from the top of a building. The ball leaves the thrower’s hand with a speed of 10m/s.
a) What is the speed after falling for 1s? 2s? 3s?
Answer:

b) How far does it fall in 1s? 2s? 3s?
Answer:

c) What is the magnitude of its velocity after falling 10m?
Answer:

Answer 1

\[
\textrm{Always compare your givens and needs with the equations of motion.}
\\ \
\\ \ \ \ \ v = v_o + at
\\ \ \ \ \ s = s_o + v_ot + \frac{1}{2} at^2
\\ \ \ \ \ s = s_o + \frac{1}{2}(v-v_o)t
\\ \ \ \ \ v^2 = v_o^2 + 2a(s-s_o)

\\ \
\\ s_o = \textrm{initial displacement}
\\ s = \textrm{final displacement}
\\ v_o = \textrm{initial velocity}
\\ v = \textrm{final velocity}
\\ a = \textrm{acceleration}
\\ t = \textrm{time}
\\ \
\\ A)
\\ \textrm{Given:}
\\ s_o = 0
\\ v_o
\\ a
\\ t
\\ \
\\ \textrm{Need:}
\\ v
\\ \
\\ \textrm{Which equation might you use?}
\\ \
\\ B)
\\
\\ \textrm{Need:}
\\ s
\\ \
\\ \ \textrm{Given:}
\\ s_o = 0
\\ v_o
\\ a
\\ t
\\ \
\\ \ C)
\\ \ \textrm{Need:}
\\ \ v
\\ \
\\ \ \textrm{Given:}
\\ s_o = 0
\\ s
\\ a
\\ v_o
\]

Answer 2

Also remember that the initial velocity as well as resultant velocities are in the same direction as the accelerations (gravity)