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. Satellite centripetal acceleration Earth orbital velocity

3. Force on Mass  Newton’s law of acceleration applies to orbits. Centripetal acceleration times mass is the force of gravityCentripetal 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 Earth a F

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. Earth a F net F net = mg a = g v v

5. Weightlessness  Objects in free fall exert no normal force. F net = -ma = -mg + F NF net = -ma = -mg + F N If a = g, F N = 0If a = g, F N = 0  The same is true in orbit. F net = ma r = F grav + F NF net = ma r = F grav + F N If a r = F grav /m, F N = 0If a r = F grav /m, F N = 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.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. F net = ma r = F NF net = ma r = F N  The net force must be due to a normal force. Experience as weightExperience as weight If r  2 = g then it matches earth’s gravity.If r  2 = g then it matches earth’s 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 =  2 r