I am taking the basic physics class thru Udacity. This blog is my scratch pad and results as I work my way thru the class. In addition, I am refreshing myself on basic calculus
Monday, July 9, 2012
Unit 2 - Problem 2 => Man in elevator
The man weighs 800 newtons and wants to weigh 600 newtons. Find the man's mass first where gravity is 10 m/s/s.
F = m*a
m = \frac{F}{a} = \frac{800}{10} = 80\;{kilograms}
Now find the acceleration that would make this mass weigh 600 newtons.
a = \frac{F}{m} = \frac{600}{80} = 7.5\frac{m}{s^2}
The downward acceleration to reduce the overall acceleration is:
7.5 = g - a_{down}
a_{down} = g - 7.5 = 10 - 7.5 = 2.5 \frac{m}{s^2}
The distance down traveled in 5 seconds, assuming starting from a dead stop, is given by:
y_{down} = \frac{1}{2} a t^2 = .5 * 2.5 * (5*5) = 31.25 m
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