- #1
Masrat_A
Homework Statement
A baby falls from the top of a ##45 m## building. What is the minimum speed that Spiderman must push off from the same building one second later in order to catch the baby before she strikes the ground?
Homework Equations
Please see below.
The Attempt at a Solution
I tried my hand at solving to, unfortunately, no avail.
##v_{0y} - at = 0##
##10t = 45##
##t = 4.5##
##v_y = 45 - 10(4.5)##
##v_y = 0##
Here is the solution of a friend (which I feel is right), though he did not have enough time to explain his process.
##5t^2 +45 = 0##
##5t^2 = 45##
##t^2 = 9##
##t = 3 s##
##-5(2)^2 - v(2) +45 = 0##
##-20 - 2v + 45 = 0##
##25 - 2v = 0##
##2v = 25##
##v = 12.5##
Could anyone please explain to me what formulas had been used in the two parts to find time and velocity, and precisely how they were utilized?
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