Lecture 4:  1-Dimensional Motion

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Motion with Constant Acceleration Motion in the y-direction: free fall
Motion in the y-direction has very special characteristics.  For instance, if you throw a stone straight up into the air with an initial velocity of 20 m/s, the following are true:

• The velocity of the stone when it reaches it's maximum height is equal to zero
• The acceleration of the stone no matter where it is in it's path is always equal to 9.80 m/s² and directed downward.
• The velocity of the stone when it returns to it's starting position is equal to it's initial velocity but directed downward: so for this example it is -20 m/s.
• The time it takes for the stone to return to it's starting position is equal to 2 times the time it takes to reach it's maximum height.

The equations used for free fall or motion in the y-direction are the following:
                            y = y_o +v_ot -(1/2)gt²
                            v = v_o - gt
                            y = y_o  + (1/2)(v+v_o)t
                            v² = v_o² - 2g(y - y_o )
The rest of the lecture will be dedicated to problem solving.

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