How would i Work out this physics problem?

Question

The greatest height reported for a jump into an airbag is 99.4 m by stuntman Dan Koto. In 1948 he jumped from rest from the top of the Vegas World Hotel and Casino. He struck the airbag at a speed of 39 m/s (88 mi/h). To assess the effects of air resistance, determine how fast he would have been traveling on impact had air resistance been absent.

I don't even know what i'm finding exactly not to speak of how to find it lol

Explanations please....I'm trying to learn and not just finish my HW assignment

Answer 1

You need to find out how fast the stuntman would be hitting the airbag in a vacuum (no air to hold him back), then see the difference the air made.

The formula you need is as follows v^2= 2gd, where

v is the velocity in m/s

g is the acceleration due to gravity (9.8 m/s/s)

d is the distance fell (in meters)

So...

v^2 = 2(9.8m/s/s)(99.4m)...  doing all the math gives you

44.14 m/s

That means the air resistance accounted for approximately 5.14 m/s, or about 11.5 mph.

Hopes this helps...

Answer 2

conservation of energy

h=99.4m

his height gives you potential energy (E=mgh)

work it out without numbers first

E(pot)=E(Kin)

at first he has potetnial energy due to height h

when he is falling that energy transfers into kinetic, without friction (or air resistance), they are the same, again conservation

mgh=1/2mv^2

m cancels out and you are left with:

v=sqrt(2gh)=sqrt(2*9.81*99.4)=44.2 m/s