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Apparent Weight

How can NASA provide a sensation of weightlessness without the expense and high risk of sending astronauts into space?. Apparent Weight. Our perception of weightlessness is really the absence or reduction of normal (contact) forces acting upon our body.

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Apparent Weight

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  1. How can NASA provide a sensation of weightlessness without the expense and high risk of sending astronauts into space?

  2. Apparent Weight Our perception of weightlessness is really the absence or reduction of normal (contact) forces acting upon our body. Conversely, we can feel heavier if the normal (contact) forces acting on us are larger than normal. Think about the forces you experienced on the Demon Drop or Power Tower at Cedar Point

  3. Apparent Weight in an Elevator Now suppose you stand on the bathroom scale and ride an elevator up and down. Asyou are accelerating upwards and downwards, the scale reading is different than when you are at rest and traveling at constant speed. Which situation does Anna Litical feel the heaviest? Which situation does she feel the lightest?

  4. Apparent Weight in an Elevator - Graphs #3 #5 WT #2 #4 #6 #1

  5. Apparent Weight in an Elevator - Graphs FN #3 #5 wT #2 #4 #1 #6 Time (s)

  6. Apparent Weight in an Elevator - Concepts A body at rest wants to stay at rest so when the elevator starts to move down there is less force pushing on your feet. #1 There is no change in motion so the upwards push on your feet must be equal and opposite to your weight #2 #3 Your body wants to keep moving at constant speed but the elevator is slowing down so more force is exerted on your feet #4 The elevator is at rest so the force on your feet must be equal and opposite to your weight #5 Your body wants to remain at rest but the elevator starts to move upwards. This imparts more upwards force on your feet than your weight #6 Your body wants to move upwards at constant speed but the elevator slows down so there is less force on your feet

  7. Apparent Weight in an Elevator Coming Down - Concept FBD’s FNET a a FNET Elevator starts accelerating downwards FNET = m a (down) FN < Fg Elevator at rest Zero Acceleration FNET = 0 FN = Fg Elevator at constant speed downwards Zero Acceleration FNET = 0 FN = Fg Elevator is slowing down to a stop while moving down FNET = m a (up) FN > Fg The normal Force (orange) is what she feels

  8. Apparent Weight in an Elevator Coming Down - Theory FNET a a FNET FNET = m a (down) FNET = 0 FN = Fg = mg FNET = 0 FN = Fg = mg FNET = m a (up) FNET = Fg - FN FNET = FN - Fg Weigh normal mg - FN = ma Weigh normal FN -mg = ma FN = mg - ma FN = ma + mg FN = m(g - a) FN = m(g + a) Weigh less Weigh more

  9. Apparent Weight in an Elevator Going Up - Concept FBD’s a a FNET FNET Elevator starts accelerating upwards FNET = m a (up) FN > Fg Elevator at constant speed upwards Zero Acceleration FNET = 0 FN = Fg Elevator is slowing down to a stop while moving up FNET = m a (down) FN < Fg Elevator at rest Zero Acceleration FNET = 0 FN = Fg

  10. Apparent Weight in an Elevator Going Up - Theory a a FNET FNET FNET = m a (up) FNET = 0 FN = Fg = mg FNET = 0 FN = Fg = mg FNET = m a (down) FNET = FN - Fg FNET = Fg - FN FN -mg = ma Weigh normal Weigh normal mg - FN = ma FN = ma + mg FN = mg - ma FN = m(g + a) FN = m(g - a) Weigh more Weigh less

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