Artificial Gravity

1
Artificial Gravity
2
Central Force

• There is no normal or tension force affecting
  things in orbit.
• Like falling bodies that accelerate, a satellite
  accelerates toward the earth.
• Gravity is a central force.

orbital velocity
centripetal acceleration
Satellite
Earth
3
Force on Mass

• Newtons law of acceleration applies to orbits.
• Centripetal acceleration times mass is the force
  of gravity
• The situation is the same for the satellite or
  any object in the satellite.

Satellite or astronaut
F
a
Earth
4
Free Fall

• The net force of an object in circular orbit
  matches the centripetal acceleration.

• This is the same for a freely falling object.
• Velocity does not change the force or
  acceleration.

v
Fnet
a
a g
Fnet mg
v
Earth
5
Weightlessness

• Objects in free fall exert no normal force.
• Fnet -ma -mg FN
• If a g, FN 0
• The same is true in orbit.
• Fnet mar Fgrav FN
• If ar Fgrav/m , FN 0
• Objects in orbit are weightless.

6
Spin the Station

• A spinning station in orbit has a centripetal
  acceleration of its own.
• Acceleration is on the inside pointing inward.
• There is a corresponding centripetal force for
  object on the inside wall.

Satellite
a
F
7
Station Gravity

• The centripetal force is like an elevator
  accelerating upward.
• Fnet mar FN
• The net force must be due to a normal force.
• Experience as weight
• If rw2 g then it matches earths gravity.

Satellite
a
F
8
Centrifuge

• A centrifuge spins to create an artificial
  gravity.
• Liquid separation
• Pilot training
• Amusement rides

9
Gravitron

• The Gravitron is an amusement ride that uses
  centripetal force.
• Rotates at 24 rpm
• Diameter is 14 m

10
Centripetal Correction

• The spin of the earth creates a centripetal
  acceleration toward the axis of the earth.
• The effect is like accelerating down in an
  elevator.
• Items weigh less at the equator.

a w2r