Physics 210 Problems - My Solutions
Dr. Hulan E. Jack Jr.
Chapter 2 P6
Serway, Faughn and Vuille: College Physics 8th Edition , Thomson Brooks/Cole, Vol I(ISBN #) 978-049511374-3
THE PROBLEM STATEMENT
Ch2 6. A graph of position versus time for a certain particle moving
along the x-axis is shown in Figure P2.6.
Find the average velocity in the time intervals from
(a) 0 to 2.00 s,
(b) 0 to 4.00 s,
(c) 2.00 s to 4.00 s,
(d) 4.00 s to 7.00 s, and
(e) 0 to 8.00 s .
Page 1 of 3
Physics 210 Problems - My Solutions
Dr. Hulan E. Jack Jr.
Ch2 6. A graph of position versus time for a certain particle moving
along the x-axis is shown in Figure P2.6.
Find the average velocity in the time intervals from
(a) 0 to 2.00 s,
(b) 0 to 4.00 s,
(c) 2.00 s to 4.00 s,
(d) 4.00 s to 7.00 s, and
(e) 0 to 8.00 s .
BRAINSTORMING-Definitions, concepts ,
principles and Discussion
The average velocity, va , is the slope of the end points of the x vs. t graph. That is
va = x/t(of end points of the interval) = (x endtime – x starttime)/(endtime – starttime)
For example,
va (2.0s,0.0s) ,
endtime =2.0s, starttime = 0.0s, and x endtime = 10m and x starttime = 0m.
So,
va (2.0s,0.0s) = (x endtime – x starttime)/(endtime – starttime) = (10m-0m)/(2s-0s) = 10m/2s =5m/s.
Page 2 of 3
Physics 210 Problems - My Solutions
Dr. Hulan E. Jack Jr.
Ch2 6. A graph of position versus time for a certain particle moving
along the x-axis is shown in
Figure P2.6.
Find the average velocity in the
time intervals from
(a) 0 to 2.00 s,
(b) 0 to 4.00 s,
(c) 2.00 s to 4.00 s,
(d) 4.00 s to 7.00 s, and
(e) 0 to 8.00 s .
(4
,2
)
0)
(4,
(8,0)
1 2 3 4 5 6 7 8
,
(7
4)
Basic Solution
10
8
6
4
2
0
-2
-4
-6
(2,0
)
x(m)
t(s)
Follow the almost color matching between graphs and va calculation.
va = x/t(of end points of the interval) = (x endtime – x starttime)/(endtime – starttime)
endtime =2.0s, starttime = 0.0s, and x endtime = 10m and x starttime = 0m.
va (2.0s,0.0s) = (x endtime – x starttime)/(endtime – starttime) = (10m-0m)/(2s-0s) = 10m/2s =5m/s.
endtime =4.0s, starttime = 0.0s, and x endtime = 5m and x starttime = 1m.
va (4.0s,0.0s) = (x endtime – x starttime)/(endtime – starttime) = (4m-0m)/(4s-0s) = 4m/4s =1m/s.
endtime =4.0s, starttime = 2.0s, and x endtime = 4m and x starttime = 10m.
va (4.0s,2.0s) = (x endtime – x starttime)/(endtime – starttime) = (4m-10m)/(4s-2s) = -6m/2s =-3m/s.
endtime =7.0s, starttime = 4.0s, and x endtime = -5m and x starttime = 4m.
va (7.0s,4.0s) = (x endtime – x starttime)/(endtime – starttime) = ((-5m)-4m))/(4s-2s) = -9m/2s = 4.5m/s.
endtime =8.0s, starttime = 0.0s, and x endtime = 0m and x starttime = 0m.
va (8.0s,0.0s) = (x endtime – x starttime)/(endtime – starttime) = (0m)-0m))/(4s-2s) = 0m/2s = 0m/s.
Page 3 of 3