Starting from rest at point A, you ride your motorcycle north (the direction) to
ID: 1608246 • Letter: S
Question
Starting from rest at point A, you ride your motorcycle north (the direction) to point B 95.0 m away, increasing speed at a steady rate of 1.55 m/s2. You then gradually turn toward the east (the î direction) along a circular path of radius 45.0 m at constant speed from B to point C, until your direction of motion is due east at C. You then continue eastward, slowing at a steady rate of 1.1 m/s2 until you come to rest at point D.
(a) What is your average velocity and acceleration for the trip from A to D?
vavg = m/s
aavg = 0 m/s2
(b) What is your displacement during your trip from A to C?
m
(c) What distance did you travel for the entire trip from A to D?
m
Explanation / Answer
from A to B
y = voy*t1 + (1/2)*ay*t1^2
95 = (1/2)*1.55*t2^2
t1 = 11.1 s
displacement rAB = 95 j
=============
from B to c
vB = sqrt(2*ay*y) = sqrt(2*1.55*95) = 17.2 m/s
time t2 = distance/time = (piR/2)/vBpi*R/(2*vB) = (pi*45)/(2*17.2)
t2 = 4.11 s
displacement r2 = R*cos45i + R*sin45 j
rBC = 45*cos45i + 45*sin45 j = 31.82i + 31.82 j
-----------
from C to D
displacement r3 = vB^2/(2*ax) i = 17.2^2/(2*1.1) = 134.47 i
rCD = vB*t3 + (1/2)*ax*t3^2
134.47 = (17.2*t) - (0.5*1.1*t^2)
134.47 = (17.2*t3) - (0.5*1.1*t3^2)
t3 = 15.7 s
================
(a)
average velocity
total displacemement r = r1 + r2 + r3
r = 95j + 31.82i + 31.82 j + 134.47 i
r = 166.29 i + 126.82 j
magnitude r = sqrt(166.29^2+126.82^2) = 209.13 m
Vavg = d/T = 209.13/(11.1+4.11+15.7) = 6.76 m/s
aavg = 0
===================
(b)
A to C
rAC = rA + rC = 95j + 31.82i + 31.82 j
rAC = 31.82 i + 126.82 j
rAC = sqrt(31.82^2+126.82^2) = 130.57 m <<<<<--answer
(c)
distance = 95 + (pi*45/2) + 134.47 = 300.1 m <<<------answer
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