Physics
posted by Isis .
An object is dropped from a platform 100 feet high. Ignoring wind resistance, what will its speed be when it reaches the ground?
_____ ft/s
Please help me!!!

solution
height(h)= 100ft
since the object starts at rest,
initial speed(U)=0
Final speed (v)= ?
since the object is falling under the influence of gravity and downwards
a=g= 32.17 ft/s^2
so
we have
v2=u2+2gh
v2= 0+ 2*32.17*100
v2= 6434
v=80.21f/s
the final speed was 80.21 f/s 
An object is dropped from a platform 100 feet high.ignoring wind resistance,how long will it take to reach the ground ?

d=1/2gt^2
acceleration due to gravity= 32 ft/s^2
100= 1/2(32)t^2
100=16t^2
100/16 = 6.25
t^2= 6.25
t= 2.5 
Light travels approximately 982,080,000 ft/s, and one year has approximately 32,000,000 seconds. A light year is the distance light travels in one year.
State the speed in mi/s, using scientific notation. (1 mile = 5280 feet exactly, by definition; i.e., this is not a measurement.) 
An object is thrown directly up (positive direction) with a velocity (vo) of 20.0 m/s and do= 0. How high does it rise (v = 0 cm/s at top of rise). Remember, acceleration is 9.80 m/s2.