CoE questions

PFY p.121

a) Weight = mg

= 50x10

= 500 N

b) GPE = mgh

= 500x4

= 2,000 J

c) Total energy at start = Total energy at end

= 2,000 J 

Collins, p.91

a) GPE = mgh

= 35x10x30

= 10,500 J

b) Energy at start = Energy at end

KE = (1/2)mv^2

10500 = (1/2)x35xv^2

600 = v^2

v = 10√6 = 24.5 m/s

c) Because the friction force causes the sledge to slow down, therefore the velocity is lesser than what we calculated, as well as the air resistance.