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Phy 201
Your 'cq_1_13.1' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.
** CQ_1_13.1_labelMessages **
Copy the problem below into a text editor or word processor.
• This form accepts only text so a text editor such as Notepad is fine.
• You might prefer for your own reasons to use a word processor (for example the formatting features might help you organize your answer and explanations), but note that formatting will be lost when you submit your work through the form.
• If you use a word processor avoid using special characters or symbols, which would require more of your time to create and will not be represented correctly by the form.
• As you will see within the first few assignments, there is an easily-learned keyboard-based shorthand that doesn't look quite as pretty as word-processor symbols, but which gets the job done much more efficiently.
You should enter your answers using the text editor or word processor. You will then copy-and-paste it into the box below, and submit.
________________________________________
A ball rolls off the end of an incline with a vertical velocity of 20 cm/s downward, and a horizontal velocity of 80 cm/s. The ball falls freely to the floor 120 cm below.
• For the interval between the end of the ramp and the floor, hat are the ball's initial velocity, displacement and acceleration in the vertical direction?
As soon as the ball reaches the end of the ramp, its vertical velocity is 20cm/s, vertical displacement is 0 (since it hasn’t fallen the 120cm yet), and vertical acceleration will be 9.8m/s^2
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• What therefore are its final velocity, displacement, change in velocity and average velocity in the vertical direction?
Final velocity would be 0 since it hits the floor, final displacement will be 120cm, change in velocity would be 20 (going from 20 to 0), and average velocity would be 10cm/s.
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The ball doesn't come to rest until after it hits the floor.
As soon as it touches the floor its acceleration will change and the analysis of the fall by means of the equations of uniformly acceleration motion must cease (since acceleration will change in the next instant, it will no longer be uniform).
The final velocity is therefore the velocity it attains during the fall, and before the floor has slowed it.
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As the ball falls its acceleration is 9.8 m/s^2 or, equivalently, 980 cm/s^2 dowwnard.
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• What are the ball's acceleration and initial velocity in the horizontal direction, and what is the change in clock time, during this interval?
Horizontal initial velocity is 80cm/s
I assume acceleration would be less than 1cm/s^2 since the ball must be slowing down.
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The ball will slow in the horizontal direction if, and only if, there is a nonzero net force in that direction.
Gravity acts straight down. Its component in the horizontal direction is zero.
We assume that air resistance, which would exert a force in the horizontal direciton, is negligible at this speed and is therefore effectively zero.
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‘dt = somewhere around 1 or 2 seconds I guess
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You can find `dt by analyzing the vertical motion.
It takes less than a second for a freely falling object to fall 120 cm.
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• What therefore are its displacement, final velocity, average velocity and change in velocity in the horizontal direction during this interval?
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• After the instant of impact with the floor, can we expect that the ball will be uniformly accelerated?
If there is no friction across the floor, then the ball will continue rolling uniformly
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That would be the case for the horizontal motion.
However, pre my previous note, the analysis ends at the instant of first contact with the floor.
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• Why does this analysis stop at the instant of impact with the floor?
The balls vertical velocity should be 0. Also we only need the information of how far the ball traveled while it was still in the air, the way the ball rolls after impact with the floor is not related to any of the vertical information.
; we are more interested in the ramp and ball as a projectile, not what happens after that projectile stops falling.
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** **
25 minutes
** **
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The analysis cannot extend beyond the instant of first contact with the floor, at which time the floor will not yet have begun to slow the ball.
&#Please see my notes and submit a copy of this document with revisions, comments and/or questions, and mark your insertions with &&&& (please mark each insertion at the beginning and at the end).
Be sure to include the entire document, including my notes. &#
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#$&*
Phy 201
Your 'cq_1_13.1' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.
** CQ_1_13.1_labelMessages **
Copy the problem below into a text editor or word processor.
• This form accepts only text so a text editor such as Notepad is fine.
• You might prefer for your own reasons to use a word processor (for example the formatting features might help you organize your answer and explanations), but note that formatting will be lost when you submit your work through the form.
• If you use a word processor avoid using special characters or symbols, which would require more of your time to create and will not be represented correctly by the form.
• As you will see within the first few assignments, there is an easily-learned keyboard-based shorthand that doesn't look quite as pretty as word-processor symbols, but which gets the job done much more efficiently.
You should enter your answers using the text editor or word processor. You will then copy-and-paste it into the box below, and submit.
________________________________________
A ball rolls off the end of an incline with a vertical velocity of 20 cm/s downward, and a horizontal velocity of 80 cm/s. The ball falls freely to the floor 120 cm below.
• For the interval between the end of the ramp and the floor, hat are the ball's initial velocity, displacement and acceleration in the vertical direction?
As soon as the ball reaches the end of the ramp, its vertical velocity is 20cm/s, vertical displacement is 0 (since it hasn’t fallen the 120cm yet), and vertical acceleration will be 9.8m/s^2
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• What therefore are its final velocity, displacement, change in velocity and average velocity in the vertical direction?
Final velocity would be 0 since it hits the floor, final displacement will be 120cm, change in velocity would be 20 (going from 20 to 0), and average velocity would be 10cm/s.
@&
The ball doesn't come to rest until after it hits the floor.
As soon as it touches the floor its acceleration will change and the analysis of the fall by means of the equations of uniformly acceleration motion must cease (since acceleration will change in the next instant, it will no longer be uniform).
The final velocity is therefore the velocity it attains during the fall, and before the floor has slowed it.
*@
@&
As the ball falls its acceleration is 9.8 m/s^2 or, equivalently, 980 cm/s^2 dowwnard.
*@
#$&*
• What are the ball's acceleration and initial velocity in the horizontal direction, and what is the change in clock time, during this interval?
Horizontal initial velocity is 80cm/s
I assume acceleration would be less than 1cm/s^2 since the ball must be slowing down.
@&
The ball will slow in the horizontal direction if, and only if, there is a nonzero net force in that direction.
Gravity acts straight down. Its component in the horizontal direction is zero.
We assume that air resistance, which would exert a force in the horizontal direciton, is negligible at this speed and is therefore effectively zero.
*@
‘dt = somewhere around 1 or 2 seconds I guess
@&
You can find `dt by analyzing the vertical motion.
It takes less than a second for a freely falling object to fall 120 cm.
*@
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• What therefore are its displacement, final velocity, average velocity and change in velocity in the horizontal direction during this interval?
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• After the instant of impact with the floor, can we expect that the ball will be uniformly accelerated?
If there is no friction across the floor, then the ball will continue rolling uniformly
@&
That would be the case for the horizontal motion.
However, pre my previous note, the analysis ends at the instant of first contact with the floor.
*@
#$&*
• Why does this analysis stop at the instant of impact with the floor?
The balls vertical velocity should be 0. Also we only need the information of how far the ball traveled while it was still in the air, the way the ball rolls after impact with the floor is not related to any of the vertical information.
; we are more interested in the ramp and ball as a projectile, not what happens after that projectile stops falling.
#$&*
** **
25 minutes
** **
@&
The analysis cannot extend beyond the instant of first contact with the floor, at which time the floor will not yet have begun to slow the ball.
&#Please see my notes and submit a copy of this document with revisions, comments and/or questions, and mark your insertions with &&&& (please mark each insertion at the beginning and at the end).
Be sure to include the entire document, including my notes. &#
*@