PHYS 1P21 Lecture Notes - Lecture 4: Roof Tiles, One Direction, Stopwatch
16 May 2016
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PHYS 1P21 Full Course Notes
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Page 54, problem 44 a dynamite blast at a quarry launches a chunk of rock straight upward, and. 2. 0 s later it is rising at a speed of 15 m/s. Assuming air resistance does not exist, calculate the speed of the rock (a) at launch, and (b) 5. 0 s after launch. Discussion: choose up to be the positive direction. Then the acceleration due to gravity is 9. 8 m/s2, because the acceleration due to gravity points down, which is the negative direction. Let t= 0 represent the time at which the rock is launched. Thus, we are looking for the speeds of the rock at t= 0 and t= 5 s. Thus, the initial speed of the rock is 34. 6 m/s and the speed of the rock after 5 s is 14. 4 m/s. Page 54, problem 46 a ball is thrown vertically upward, and 8. 0 s later the ball returns to its point of release.
