To meet a U.S. Postal Service requirement, footwear must have a coefficient of static friction of 0.5 or more on a specified surface. In an emergency, what is the minimum time interval in which a person starting from rest can move a distance L on a tile surface if she is wearing footwear meeting the Postal Service minimum?
It's either:
a)2sqrt(g/L)
b)4(L/g)
c)sqrt(L/g)
d)2sqrt(L/g)

I'm not too sure on this one, I would think that the mass of the person would come into it, but none of the answers include that.

You need to draw it up and start applying the formulae that you have learnt in class.

Sorry I can't be of more help right now.

I would like to share with you a little secret for doing multiple choice questions.

Here you have:

a)2sqrt(g/L)
b)4(L/g)
c)sqrt(L/g)
d)2sqrt(L/g)

Looking at how these are structured, you can come to some conclusions:
1. the correct answer probably has a squareroot in it, because 3 of the choices have a square root, this eliminates b.
2. the correct answer probably has L/g and not g/L, since L/g appears in 3 of the choices, this eliminates a
3. the correct answer is likely to be d, because a and d both have the same coefficients, 2sqrt, and we have already eliminated a from observation 2.

So I would go for d, but I'd like to see how the answer works out.

This is likely to work over 50% of the time, which is much better than the 25% odds you get for guessing randomly :)