Monday, September 12, 2011

CoE questions

19. a) 500N/kg

b) GPE = mgh

     GPE = 50 x 10 x 4 = 2000J

c) KE = ½ m v2

     KE = 0.5 x 50 x 2000 =  50000m/s2

Q3. A) GPE = mgh

            GPE = 35 x 10 x 30 = 10,500J

B) KE = ½mv2

     But KE (bottom) = GPE (top)

        10,500 = ½ x 35 x v2

        v2 = 600

        v = 24.5m/s

C) because some of it got wasted by heat through friction

 

PFY p.121

Image001

 

Collins, p.91

Image002

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