PHY 201
Your 'cq_1_6.1' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.
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Seed Question 6.1
For each situation state which of the five quantities v0, vf, `ds, `dt and a are given, and give the value of each.
A ball accelerates uniformly from 10 cm/s to 20 cm/s while traveling 45 cm.
answer/question/discussion:
v0 = 10 cm/s
vF = 20 cm/s
'ds = 45 cm
'dt = ?
a = ?
To find 'dt:
'ds = vAve * 'dt
45 = 30/2 * 'dt
45 = 15 * 'dt
'dt = 3 seconds
To find a:
a = 'dv/'dt
a = 10/3
a = 3.3 cm/s/s
A ball accelerates uniformly at 10 cm/s^2 for 3 seconds, and at the end of this interval is moving at 50 cm/s.
answer/question/discussion:
a = 10 cm/s/s
'dt = 3 seconds
vF = 50 cm/s
'ds = ?
v0 = ?
To find v0:
a = (vF-v0)/ 'dt
10 = (50 - v0)/ 3
30 = 50 - v0
v0 = 20 cm/s
To find 'ds:
'ds = vAVe * 'dt
'ds = 70/2 * 3
'ds = 35 * 3
'ds = 105 cm
A ball travels 30 cm along an incline, starting from rest, while accelerating at 20 cm/s^2.
answer/question/discussion:
v0 = 0
'ds = 30 cm
a = 20 cm/s/s
vF = ?
'dt = ?
a = 'dv/'dt
'dt = 'dv/a
'ds = vAVe * ('dv/a)
30 = (0 + vF)/2 * (vF - 0)/a
30 = vf/2 * vf/a
60a = vf^2
60(20) = vf^2
1200 = vf^2
vf = 34.64
excellent work
The third and fourth equations of motion could also be used, but I very much like the way you put together the definitions of velocity and acceleration to get your results.
30 = 34.64/2 * t
'dt = 1.73
Then for each situation answer the following:
Is it possible from this information to directly determine vAve?
answer/question/discussion:
IN the first question yes. vAve = 15 cm/s
In the second question you are not given initial velocity but can find it in the acceleration equation, then just add final v and divide by 2 to get 35 cm/s
IN the third question no, you have to use formulas instead of direct reasoning.
Is it possible to directly determine `dv?
answer/question/discussion:
In the first question yes. 'dv = 10 cm/s
In the second question you are not given initial velocity but can find it in the acceleration equation, then just subtract it from vF to get 30 cm
IN the third question no, you have to use formulas instead of direct reasoning.
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45 minutes
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Excellent work. Be sure to see my note.