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*#&!*#&!
course PHY 241
420pm 10/15/2011
Randomized Assignment 2 Problem 1 If the velocity of the object
changes from 4 cm / sec to 16 cm / sec in 8 seconds, then at what
average rate is the velocity changing?
V_a = 4 cm/sec @ t=0 sec
V_b = 16 cm/sec @ t=8 sec
(V_b - V_a)/ 8 secs = (12 cm/sec) / 8 sec = 1.5 cm/sec
@& (cm / s) / s is not cm/s.*@
A ball rolling from rest down a constant incline requires 8.2 seconds
to roll the 97 centimeter length of the incline.
What is its average velocity?
97 cm/ 8.2 seconds = 11.8 cm/sec
An object which accelerates uniformly from rest will attain a final
velocity which is double its average velocity.
What therefore is the final velocity of this ball?
23.6 cm/sec
What average rate is the velocity of the ball therefore changing?
(23.6 cm/sec) / (8.2 sec) = 2.9 cm/sec
@&(cm/s) / s does not give you cm/s. *@
An automobile accelerates uniformly down a constant incline, starting
from rest. It requires 10 seconds to cover a distance of 132 meters.
At what average rate is the velocity of the automobile therefore
changing?
132 meters/ 10 seconds = 13.2 m/sec
v_f = 13.2 m/sec * 2 = 26.4 m/sec
(26.4m/sec) / 10 sec = 2.64 m/sec
@& You unit here is incorrect.*@
@& RIght reasoning and right procedures, but your units are often incorrect. You need to actually do the algebra of the units.*@