# Physics

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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

• Physics -

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

• Physics -

An object is dropped from a platform 100 feet high.ignoring wind resistance,how long will it take to reach the ground ?

• Physics -

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

• Physics -

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.)

• Physics -

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.

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