a student drops an object out the window of the top floor of a high-rise dormitory

a) neglecting air resistance, how fast is the object traveling when it strikes the ground at the end of 3.0 s? express the speed in mi/h for a familiar comparison,

b) how far, in meters, does the object fall during the 3.0 s? How many floors does the dormitory probably have?

6 answers

come on now, use what we have done
v = g t

but to go from m/s to mi/hr
use
3600 seconds / hour
and 1609 meters/mile

a floor is about 3 meters
WORK IN METRIC
convert later if dealing with carpenters.
is it d = 1/2 (9.8) (3)^2 = 44.1 m/s^2/3s =14.7 m/s x 2 = 32.87 = 32.87 mi/h?
and

b) d= 1/2 (9.8) (3)^2 =44.1 m/s^2/35 = 14.7 m/s
You are terrribly fouled up with units. Give me a minute
the ground is 3 seconds down
d = (1/2) (9.81) (3)^2 correct

d = 44.1 METERS (THAT IS PART B)

(that is 9.81 m/s^2 * 9 s^2 so just m or meters)

NOW THE SPEED (Part A)
v = g t
v = 9.81 m/s^2 * 3 s = 29.4 m/s
(THAT IS PART A)
BUT they want miles/ hr
so
29.4 m/s * 1 mile/1609 m * 3600 s/h
= 65.8 miles/hour