#$&*
PHY 201
Your 'cq_1_25.1' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.
** **
SEED Question 25.1
A steel ball of mass 110 grams moves with a speed of 30 cm / second around a circle of radius 20 cm.
• What are the magnitude and direction of the centripetal acceleration of the ball?
answer/question/discussion: ->->->->->->->->->->->-> :
The centripetal acceleration of the ball is: 30 cm/s = 0.3 m/s, 20 cm = 0.2 m
a = v^2 / r
a = (.30 m/s)^ 2 / (0.2m)
a = 0.45 m/s^2
The magnitude is:
c^2 =0.30 m/s^2 + 0.2 m^2
c^2 = 0.09 m^2/s^2 + 0.04 m^2
c^2 = 0.13 m^2/s^2
c = sqrt (0.13 m^2/s^2)
c = 0.36 m/s = hypotenuse
@& You can't add m^2 / s^2 to m^2; this calculation would not have a meaning.
The magnitude of the acceleration is .45 m/s^2.*@
The direction is:
x = h cos (theta) = x / h cos (theta) = (theta) = cos^-1 (x / h)
(theta) = cos^-1 (0.30 m/s / 0.36 m/s)
(theta) = 33.5 deg
y = h sin (theta) = y / h sin (theta) = (theta) = sin^-1 (y / h)
(theta) = sin^-1 (0.2 m/s / 0.36 m/s)
(theta) = 33.7 deg
#$&*
• What is the magnitude and direction of the centripetal force required to keep it moving around this circle?
answer/question/discussion: ->->->->->->->->->->->-> :
The centripetal force of the ball is: 110 g = 0.110 kg
F(cent) = 0.110 kg * 0.45 m/s^2
F(cent) = 0.05 N
The magnitude is:
c^2 = a^2 + b^2
The direction is:
x = h cos (theta) = x / h cos (theta) = (theta) = cos^-1 (x / h)
y = h sin (theta) = y / h sin (theta) = (theta) = sin^-1 (y / h)
#$&*
** **
25 mins
** **
SEED Question 25.1 was submitted 1 Apr 2011 around 3:20 PM.
&#See any notes I might have inserted into your document, and before looking at the link below see if you can modify your solutions. If there are no notes, this does not mean that your solution is completely correct.
Then please compare your old and new solutions with the expanded discussion at the link
Solution
Self-critique your solutions, if this is necessary, according to the usual criteria. Insert any revisions, questions, etc. into a copy of this posted document. Mark any insertions with &&&& so they can be easily identified.If your solution is completely consistent with the given solution, you need do nothing further with this problem. &#
@& 0.36 m/s is not a velocity associated with this situation.
See the discussion at the link.*@
#$&*
PHY 201
Your 'cq_1_25.1' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.
** **
SEED Question 25.1
A steel ball of mass 110 grams moves with a speed of 30 cm / second around a circle of radius 20 cm.
• What are the magnitude and direction of the centripetal acceleration of the ball?
answer/question/discussion: ->->->->->->->->->->->-> :
The centripetal acceleration of the ball is: 30 cm/s = 0.3 m/s, 20 cm = 0.2 m
a = v^2 / r
a = (.30 m/s)^ 2 / (0.2m)
a = 0.45 m/s^2
The magnitude is:
c^2 =0.30 m/s^2 + 0.2 m^2
c^2 = 0.09 m^2/s^2 + 0.04 m^2
@& m/s and m are not the same units, so these quantities cannot be added*@
c^2 = 0.13 m^2/s^2
c = sqrt (0.13 m^2/s^2)
@& m^2 / s^2 and m^2 are unlike units, and adding the two quantities does not result in a quantity with units m^2 / s^2.*@
c = 0.36 m/s = hypotenuse
The direction is:
x = h cos (theta) = x / h cos (theta) = (theta) = cos^-1 (x / h)
(theta) = cos^-1 (0.30 m/s / 0.36 m/s)
(theta) = 33.5 deg
y = h sin (theta) = y / h sin (theta) = (theta) = sin^-1 (y / h)
(theta) = sin^-1 (0.2 m/s / 0.36 m/s)
@& 0.36 m/s is not a velocity associated with this situation.
See the discussion at the link.*@
(theta) = 33.7 deg
#$&*
• What is the magnitude and direction of the centripetal force required to keep it moving around this circle?
answer/question/discussion: ->->->->->->->->->->->-> :
The centripetal force of the ball is: 110 g = 0.110 kg
F(cent) = 0.110 kg * 0.45 m/s^2
F(cent) = 0.05 N
The magnitude is:
c^2 = a^2 + b^2
The direction is:
x = h cos (theta) = x / h cos (theta) = (theta) = cos^-1 (x / h)
y = h sin (theta) = y / h sin (theta) = (theta) = sin^-1 (y / h)
#$&*
** **
25 mins
** **
SEED Question 25.1 was submitted 1 Apr 2011 around 3:20 PM.
&#See any notes I might have inserted into your document, and before looking at the link below see if you can modify your solutions. If there are no notes, this does not mean that your solution is completely correct.
Then please compare your old and new solutions with the expanded discussion at the link
Solution
Self-critique your solutions, if this is necessary, according to the usual criteria. Insert any revisions, questions, etc. into a copy of this posted document. Mark any insertions with &&&& so they can be easily identified.If your solution is completely consistent with the given solution, you need do nothing further with this problem. &#