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Unformatted text preview: January 18, 2008 PHY2053 Discussion Quiz 1 (Chapter 1 & 2.1-2.4) Name: UFID: *1. (5 pts) Newtons law of universal gravitation is represented by F = GMm/r , where F is the gravitational force, M and m are masses, and r is a length. What is the dimension of the proportionality constant G ? (Hint: Force is given by mass times acceleration.) Since the dimension of both sides should be the same, we get [F] = [G][Mm]/[r]. Plug [F] = [M][a] = MLT, [Mm] = M and [r] = L into the equation, and solve it for [G]: MLT = [G]M/L [G] = MLT ***2. (5 pts) Two boats start together and race across 50 km-wide lake and back. The boat that completes the round trip first wins. Boat A goes across at 40 km/h and returns at 40km/h. Boat B goes across at 30km/h at first, but it doubles its speed when returns at 40km/h....
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