1a. An archer is able to fire an arrow (mass 0.025 kg) at a speed of 71 m/s. If

Question

1a. An archer is able to fire an arrow (mass 0.025 kg) at a speed of 71 m/s. If a baseball (mass 0.13 kg) is given the same kinetic energy, what is its speed?

b.Consider a roller coaster that moves along the track shown in the figure below. Assume all friction is negligible and ignore the kinetic energy of the roller coaster's wheels. Assume the roller coaster starts with a speed of 15 m/s at point A. Find the speed of the roller coaster when it reaches locations B and C. (Assume hA = 36 m and hB = 18 m.)

vB = ......  m/

svC =..... m/s

Explanation / Answer

a. 0.025*71^2 = 0.13*v^2 v = 31.13 m/s b. By conservation of energy between A and B : = m*g*ha+m*Va^2/2 = m*g*hb+m*v^2/2 = v^2 = (2g(ha-hb) + Va^2) = v^2 = 577.8 = v = 24 m/s = Vb By conservation of energy between A and C : = m*g*ha+m*Va^2/2 = m*v'^2/2 = v'^2 = (2*g*ha + Va^2) = v'^2 = 930.6 = v' = 30.5 m/s = Vc

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