# Introduction to SAT II Physics

(Darren Dugan) #1

generally a bit harder than the one that came before. You should expect questions 11–13 to be
harder than questions 1–4.
Classification Question Example

``````D ire cti o ns: Each se t of le t te re d cho ice s be l ow ref ers to t he n umb e red q u est i on s
i mme d iat e ly f ol lo wi ng i t. Se l ect th e o ne l et te re d ch oi ce th at b e st an swe rs eac h q ue sti o n
and t he n b lac ke n t he corre sp on d in g sp ace on th e an swe r she e t. A c ho ice may b e use d
o nce , mo re th an on ce, or no t at all i n each se t.``````

``Que st io ns 1– 3``

``A b oy th row s a bal l st rai g ht u p in t he ai r an d th e n c atch es it ag ai n.``

1. .Which of the above graphs best represents the ball’s position with respect to time?

2. .Which of the above graphs best represents the ball’s velocity with respect to time?

3. .Which of the above graphs best represents the ball’s acceleration with respect to time?

Explanation
You can usually answer classification questions a bit more quickly than the standard five-choice
completion questions, since you only need to review one set of answer choices to answer a series
of questions.
The answer to question 1 is B. The ball’s position with respect to time can be expressed by the
equation y = –^1 / 2 gt^2 , where g is the downward, acceleration due to gravity. As we can see, the
graph of y against t is an upside-down parabola. In more intuitive terms, we know that, over time,
a ball thrown in the air will rise, slow down, stop, and then descend.
The answer to question 2 is E. The acceleration due to gravity means that the velocity of the ball
will decrease at a steady rate. On the downward half of the ball’s trajectory, the velocity will be