Phy 201
Your 'cq_1_05.1' 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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The problem:
A ball accelerates at 8 cm/s^2 for 3 seconds, starting with velocity 12 cm/s.
• What will be its velocity after the 3 seconds has elapsed?
answer/question/discussion: ->->->->->->->->->->->-> : The velocity of the ball after the 3 seconds should be 28cm/second. I get this by recognizing that after each second, the ball is increasing by a velocity of 8cm/s. It is given that the ball starts with a velocity of 12cm/s. So knowing this, after the three seconds, the ball has only had time to get to a velocity of 28cm/s.
Your reasoning looks good, but in three seconds its velocity would increase by 24 cm/s, to 36 cm/s.
It looks like you used an increase of 16 cm/s, which would correspond to only two seconds of acceleration at 8 cm/s^2.
• Assuming that acceleration is constant, what will be its average velocity during this interval?
answer/question/discussion: ->->->->->->->->->->->-> : I determined the average velocity to be 20cm/s during this time interval. I get this solution by adding the initial velocity to the final velocity and dividing by 2. So, ((28cm/s)+(12cm/s)) / 2 = 20cm/s.
• How far will it travel during this interval?
answer/question/discussion: ->->->->->->->->->->->-> : The object should travel 60cm according to my calculations. I get this quantity simply by multiplying the average to the time interval. So, (20cm/s)* 3 sec = 60cm
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this assignment took me about 15 minutes
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Your procedures are correct; you have one number that doesn't appear correct (and is then used to find some subsequent results) but it should be easy to correct this.
Final velocity should be 36 cm/s, ave velocity 24 cm/s and displacement 72 cm.
Let me know if you have questions.