Mini-Quiz: Gravity Time Equations for Objects Projected Upward

1. If the initial velocity is −32 ft/s, how long does it take for the object to reach +32 ft/s?

   t = (32 − 32)/32 = 0 secondsSorry, not correct. Try another button. t = (32 + 32)/32 = 2 secondsCorrect. You understand about gravity equations. t = 32 + 32/32 = 33 secondsGood try, but not right. Select another answer.

2. If vi = −20 m/s, which equation shows the time it takes the object to move upward and reach 30 m above the starting point?

   t = [−20 − √(−20)2 + 2*9.8*30]/9.8Oops! Wrong answer. Re-read the question and try again. t = [20 + √(−20)2 + 2*9.8*(−30)]/9.8Sorry, not correct. Try another button. t = [20 − √(−20)2 + 2*9.8*(−30)]/9.8That is Correct. You are doing great!

3. If vi = −98 m/s and y = +196 m, what is the elapsed time?

   21.8 sCorrect. You understand about gravity equations. −21.8 sOops! Wrong answer. Re-read the question and try again. 2.25 sGood try, but not right. Select another answer.

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