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Unformatted text preview: A M Kolchin/ SAR Physics Homework 5 Read Hewitt: pgs: 1724 (Please take notes on this reading). Do the following questions and problems in Hewitt at the end of chapter 2: 14,16,17,19,28,29 14 Why does the unit of time enter twice in the unit of acceleration? Acceleration is defined as the rate of change of velocity (in m/s ) per unit time (in s ). So this relationship a = Δ v Δ t involves two appearances of time units; one from velocity and one from time. 16 For a freely falling object dropped from rest, what is the instantaneous speed at the end of the fifth second of fall? The sixth second? When we drop an object from rest, Earth’s gravity pulls the object towards itself. This pull causes the object to accelerate. This acceleration, due only to the Earth’s gravity, is commonly given the symbol g . It is a constant number for Earth: g = 10 . ( m/s ) /s . Let’s identify the known quantities in the problem: Symbol Known Quantity Reference in Problem Let g = 10 ( m/s ) /s acceleration due to gravity ”freely falling object” Let v i = 0 m/s Initial speed object dropped from rest Let t i = 0 s Initial time Start clock at instant we drop object....
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 Spring '08
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 Physics, Work, Velocity, m/s, TI

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