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PH 211 Winter 2014. Wednesday January 22. Google moderator. Which topic would you like to discuss in class on Friday? http ://www.google.com/moderator/#16/e=20c5fe. Google moderator. Today’s questions: http://www.google.com/moderator/#16/e=211578. Three dimensions.
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PH 211 Winter 2014 Wednesday January 22
Google moderator Which topic would you like to discuss in class on Friday? http://www.google.com/moderator/#16/e=20c5fe
Google moderator Today’s questions: http://www.google.com/moderator/#16/e=211578
Which of the following graphs represents motion with constant acceleration? A B t x x t v C D x t v
Which of the following graphs represents motion with constant acceleration?PRESS ENTER TO SUBMIT MULTIPLE ANSERS! • A • B • C • D A B t x x t v C D x t v 0 of 208 :01
Falling bodies starting at restThey all fall with the same acceleration if one ignore air resistance, remember moon video.
Reaction time Median = 0.16 Mean = 3.48 Press 0.XX and ENTER to submit 0 of 208 :58
A rocket is launched straight up with constant acceleration. 4.0s after liftoff, a bolt falls of the side of the rocket. The bolt hits the ground 6.0s later. What was the acceleration of the rocket?
A rocket is launched straight up with constant acceleration. 4.0s after liftoff, a bolt falls of the side of the rocket. The bolt hits the ground 6.0s later. What was the acceleration of the rocket? • True • False I have an answer or I give up 137 of 208
What is known. At t=0s we have s=0m, v=0m/s At t=4.0s we change a=aup to a=-g At t=10.0s we have s=0m What we need to find: aup.
s t
Upward motion: s(t)=1/2 aup t2 v(t)=aup t Downward motion s(t)=s(4)+v(4)(t-4)-1/2 g (t-4)2 v(t)=v(4)-g(t-4) End 0=s(10)=s(4)+6v(4)-18g
Upward motion: s(t)=1/2 aup t2 v(t)=aup t End 0=s(10)=s(4)+6v(4)-18g 0= 8aup + 24 aup - 18g aup = 9g/16