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Unformatted text preview: The first appearance of Superman was in Action Comics #1 in 1938. Created b y writer Jerry Siegel and
artist Joe Shuster, his powers granted him the ability to “leap tall buildings in a single bound,” made him
“faster than a speeding bullet,” and he was “more powerful than a locomotive.” Let’s say that this yearly
version of Superman cannot fly and wants to leap to the top of a tall building (400ft.) in a single bound.
If we model him as a particle and he takes off at an angle of , what is the minimum initial speed
required to get him to the top of the building? How far away from the base of the building should he
take off? You may neglect drag on this problem.
FUNDAMENTAL FUMBLES – Before you check the solution, check these fundamental mistakes first and
make sure you can’t figure the problem out on your own.
1. Be sure your free body diagram is correct. Do you have supernatural forces acting on the particle?
2. Make sure you are consistent with time. Position, velocity, and acceleration are all functions of time,
but in order to use two equations to solve for two unknowns, you must solve the equations for the same
value of t.
3. Check your units for g. Did you use English or Metric units? Or more importantly, did the problem use
English or Metric.
4. Did you just use the equation you learned in high school? Derive it – it’s a better answer.
SOLUTION
ASSUMPTIONS
(i) Drag is negligible
(ii) Superman is a particle
(iii) Superman follows a parabolic path
(iv) The height of Superman is neglected
1. FBD mg 2. GOVERNING EQUATIONS 3. KINEMATICS COMBINING (2) and (3) At t = t0 = 0: At t = tf, the velocity in both the E1 and E2 directions is zero. (1)
We are given Superman’s final height, which corresponds to x2.
(2)
Plugging (1) into (2), 9) ...
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 Fall '09

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