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Unformatted text preview: DISCUSSION PROBLEM [2.1]: answer ... v av = displacement
time But the displacement is zero ... cars startfinish at the
same place. DISCUSSION PROBLEM [2.1]:
Estimate the average velocity of the winning car at the
Indianapolis 500 ... (total distance 500 miles in about 2 12
hours). ∴ v av = 0 However, average speed:
distance traveled 500 mi
v=
=
= 200 mi/h .
time
2.5h
Think ...
How does the
velocity vary on
each lap? 1 (a) Since the ball ends up in your hand, where it started, DISCUSSION PROBLEM [2.2]: there is no net change in position, i.e., the displacement is
zero. Hence the average velocity is zero. You lean out of a window and throw a ball straight down.
It bounces off the sidewalk and returns to your hand 2.0s (b) We cannot determine the total distance traveled by later. (a) What is the average velocity of the ball? (b) the ball since we were not told the distance from the What is its average speed? window to the ground. So, we cannot determine the
average speed using the information given. 2 DISCUSSION PROBLEM [2.3]: answer ...
Displacement (x) DISCUSSION PROBLEM [2.3]: D
C E A physics professor is walking to campus when he
realizes he’s forgotten a book and he returns home. His
B displacement as a function of time is shown below. At
which point(s) is his velocity: (a) zero? (b) constant and A time positive? (c) constant and negative? (d) increasing in
magnitude? (e) decreasing in magnitude?
Displacement (x) By definition: v = dx dt ⇒ slope
(a) v = 0 when dx dt = 0, i.e., at D D
C F E (b) dx dt is constant and positive at A
(c) dx dt is constant and negative at F B
A F
time (d) dx dt is increasing in magnitude at B and E
(e) dx dt is decreasing in magnitude at C 3 ...
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This note was uploaded on 07/13/2011 for the course PHY 2048 taught by Professor Guzman during the Spring '08 term at FAU.
 Spring '08
 Guzman
 Physics

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