Question

You throw a ball straight up into the air at a speed of 20 m/s. You want to know how high above your hand the ball will be at exactly 2.5 sec after you released it.

a) Of the 5 motion variables - Vi, Vf, a, ΔX, and T, identify which one you are solving for and the magnitudes and directions of all of the others that are known.
b) Which of the motion equations is best to use to determine the height of the ball?
c) How high is the ball above your hand at 2.5 sec after you throw it?

Answer 1

@Mashy Is this hard for you :/

Answer 2

Nah, the question is just boring :P

Answer 3

Can you tell the answer for a) ?

Answer 4

haha...

Answer 5

I don't know any of this at all! @Mashy

Answer 6

If I consider the reference system as below:

then, the motion of the ball is solved by these ODEs
\[\huge \left\{ \begin{gathered}
\ddot z = - g \hfill \\
\ddot x = 0 \hfill \\
\end{gathered} \right.\]

Answer 7

with the subsequent initial conditions:
\[\huge \begin{gathered}
\dot z\left( 0 \right) = {v_z} \hfill \\
\dot x\left( 0 \right) = {v_x} \hfill \\
z\left( 0 \right) = {h_0} \hfill \\
x\left( 0 \right) = 0 \hfill \\
\end{gathered} \]

Answer 8

we need to know te angle \(\theta\) between the velocity, and the positive direction of x-axis: