Skydiving

1
Skydiving

• By Caleb Kemp and Joshua Sick

2
How Objects Fall

• Objects are pulled by the force of gravity
• They are slowed down by friction with air
• They accelerate until they reach terminal
  velocity, that is they fall at a steady pace.

3
Our Problem

• Suppose you had a 50 kg girl and a 100 kg guy.
• What is their terminal velocity?

4
Terminal Density

• Fair -0.5p(v2)ACd
• -0.5 constant
• p density of air
• (v2) velocity squared
• A area
• Cd drag coefficient

5
Wmg

• Weight Mass times the force of gravity

6
Plug and Chug Its a physics thing

• First the 50 kg girl, lets find her weight
• 50 kg 9.81 m/s2 490.5 N
• We set this equal to our first formula with
  average area and drag coefficients
• Fair -0.5p(v2)ACd
• 490.5 N -0.5(0.0522)(v2) (1m)(0.7)
• 163.85 m/s v

7
The Big Guy

• 100 kg 9.81m/s2981N
• Fair -0.5p(v2)ACd
• 981N -0.5(0.0522)(v2) (1) (0.7)
• 231.72m/s v

8
Sources of Error

• Notice that we used the same Area for both the
  guy and the girl. In reality, the girl would
  likely have a smaller area and the man a larger
  area.
• A lot of our data was taken from averages

9
Now lets add the Parachute

• We will use the exact same formula, but plug in
  the new values of the parachute. Note the area
  of the man is neglected because it is
  insignificant to the area of the parachute.
• Fair -0.5p(v2)ACd
• 490.5 N -0.5(0.0522)(v2) (30m)(1.5)
• v 20.44 m/s

10
Second Problem

• How long does it take to reach terminal velocity
  without a parachute?
• Our formula vf vi at
• vf final velocity
• vi initial velocity
• a acceleration
• t time

11
How Acceleration Affects Terminal Velocity

• Acceleration is the rate of change.
• A skydiver accelerates until they reach terminal
  velocity.

12
Plug and Chugagain

• vf vi at
• To find the time we plug in what we know. Well
  use the womans velocity.
• 163.85m/s 0 9.81m/s2 t
• T 16.7seconds

13
Da Dudes time

• vf vi at
• 231.72m/s 0 9.81m/s2 t
• t 23.62

14
Sources of Error

• We found the approximate time of both
  individuals. The real times would vary more if
  higher level, precise math had been used.

15
Thanks

• Mr. Freivald for helping us.
• Mr. Rob for teaching usand extra credit. Please?

16
Were done now