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2.) Assuming that one story of a building is 10 feet, with what speed, in miles per hour, does an object dropped from the top of a 40-story building hit the ground?

S=s_o+ v_ot - 16t^2

0= 400 + v_oT -16t^2

????????now what?????? I have 2 unknowns

4.) A rock is thrown straight down from a height of 480 feet with an initial velocity of 16 feet per second. (a) How long does it take to hit the ground? (b) With what speed does it hit the ground? (c) How long does it take before the rock is moving at a speed of 112 feet per second? (d) When has the rock traveled a distance of 60 feet?

a.) s=s_o+v_ot-16t^2

s=480 - 16t^2

t=5.47

I can’t get part b, c, and d. How do you find the speed? The equation is for velocity. I know velocity is the magnitude of speed but how do you find it?

5.) An automobile moves along a straight highway, with its position given by

s= (12t^3)-(18t^2)+9t-(3/2)

s is in miles ans t is in hours.

(a) Describe the motion of the car: when it is moving to the right, when to the left, where and when it changes direction. (b) What distance has it traveled in the one hour from t=0 to t=1?

I have no clue.

~Thanks