Phy 201
Your 'cq_1_22.2' 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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A 70 gram ball rolls off the edge of a table and falls freely to the floor 122 cm below. While in free fall it moves 40 cm in the horizontal direction. At the instant it leaves the edge it is moving only in the horizontal direction. In the vertical direction, at this instant it is moving neither up nor down so its vertical velocity is zero. For the interval of free fall:
• What are its final velocity in the vertical direction and its average velocity in the horizontal direction?
answer/question/discussion: ->->->->->->->->->->->-> : The final velocity in the vertical direction would be 4.9m/s. I found this with the equation vf^2=vo^2+2a(ds). We then can find the horizontal velocity by finding the ‘dt using v/t=a finding that t=0.5 sec. This means that the ball was moving at 0.8m/s in the horizontal direction. I found this by taking .04m/.5 sec.
• Assuming zero acceleration in the horizontal direction, what are the vertical and horizontal components of its velocity the instant before striking the floor?
answer/question/discussion: ->->->->->->->->->->->-> : y=vf_y=4.9m/s
x=vf_x=.08m/s
• What are its speed and direction of motion at this instant?
answer/question/discussion: ->->->->->->->->->->->-> : You can use the Pythagorean Theorum to solve for the speed. This would be .08^2+4.9^2=speed^2 so the speed is about 4.9m/s
You can find the direction by taking arctan(4.9/.08) which is 90 degrees
• What is its kinetic energy at this instant?
answer/question/discussion: ->->->->->->->->->->->-> : KE=1/2(m)(v^2)
KE=1/2(.07kg)(4.9m/s)^2 which is 0.84 Joules
• What was its kinetic energy as it left the tabletop?
answer/question/discussion: ->->->->->->->->->->->-> : 0 Joules
• What is the change in its gravitational potential energy from the tabletop to the floor?
answer/question/discussion: ->->->->->->->->->->->-> : The PE would go from 0 to .84 Joules because KE is converted to PE.
• How are the the initial KE, the final KE and the change in PE related?
answer/question/discussion: ->->->->->->->->->->->-> : The initial PE is equal to the final KE and the initial KE is equal to the final PE. This is because energy is converted due to the law of conservation of energy.
• How much of the final KE is in the horizontal direction and how much in the vertical?
answer/question/discussion: ->->->->->->->->->->->-> :
KE=1/2m(v)^2 I am assuming you would just solve for each individual velocity. So I would plug in .08m/s and 4.9m/s. This gives .0002 Joules and .84 Joules. I am assuming that the .0002 is negligible.
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15 mins
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Don't refigure anything, just read the solution at the link. There are some numerical details that got lost when you used .04 m rather than .4 m for the horizontal displacement, though you did everything else correctly.
&#Please compare your solutions with the expanded discussion at the link
Solution
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