1. Artificial Gravity

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

3. Fake Gravity Artificial gravity is a fictitious force
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 earth’s gravity.
Satellite a F
Artificial gravity is a fictitious force

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

5. 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

6. Orbital Force Newton’s 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.
orbital velocity
Satellite or astronaut F a
centripetal acceleration
Earth

7. 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

8. 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.

9. Tidal Gravity The Moon’s gravity is strongest at the closest point.
Near face ocean pulled most
Far face ocean pulled least
Sides pulled slightly in
Moon’s gravity
Moon
Earth

10. Ocean Tides From Earth a person doesn’t sense the Moon’s pull.
Near and far faces of the ocean bulge away
Sides are pulled slightly in
Tides occur twice a day as Earth rotates.
Moon’s tidal pull
Moon
Earth

11. Pendulum Swing
On a turntable a pendulum doesn’t appear to swing straight.
Table turns the observer
Fictitious force
The deflection is called the Coriolis force.
Fcor
Fcor

12. Cyclone
In the absence of rotation air would move from high to low pressure.
Straight line wind
The Coriolis force causes wind to turn.
Friction causes equilibrium
Circular wind pattern around low L L