2006-09-20 13:26:33 · 8 answers · asked by Anonymous in Education & Reference ➔ Homework Help
Think of it this way.
Lets say you are standing on a road. A car passes you at 30 MPH. How fast does it look like the car is going? 30MPH (not a trick question).
Now lets say you are riding a bike down the road at 10 MPH and the car passes you at 30 MPH. How fast does it look like the car is going when it passes you? 20 MPH (30 MPH for the car minus your speed, 10 MPH).
When you weight yourself in the bathroom, your weight is equal to your mass times acceleration (F=ma). Your mass is constant no matter what. The acceleration of gravity is 9.81 m/s^2.
Now when you are on the elevator, gravity is still acting on you at 9.81 m/s^2. However, as the elevator is accelerating, you have a force that doesn't allow gravity to act on you the same way as when you are stationary (think of the cars).
For the moment the elevator is accelerating, your weight will be different. When the elevator reaches a constant speed, you will weigh the same.
I hope this makes sense
2006-09-20 13:40:16 · answer #1 · answered by Slider728 6 · 1⤊ 0⤋
If you drive at 40 miles per hour and the car in front of you drives at 50 miles per hour from your perspective it seems like he is driving 50-40=10 miles per hour away from you. In this case it is similar. acceleration is a vectoral quantity meaning direction is important. in your question both the gravity (an acceleration) and elevator is accelerating in the same direction. so you subtract elevator's acceleration from gravity, that is your net acceleration. since F=ma, you multiply your mass by that acceleration to find what the scale would read. if the elevator accelerates the same as gravity, you'd experience free fall. thats how they simulate no gravity environments in airplanes.
2006-09-20 20:40:23 · answer #2 · answered by makemovie 2 · 0⤊ 1⤋
Because the effect of gravity is being lessened by the fact that the platform you are on is falling. It would be the same principal that astronauts use to simulate zero gravity in a rapidly diving aircraft. Your enertia is being cancelled out by the falling elevator.
2006-09-20 20:36:01 · answer #3 · answered by Gregg J 2 · 0⤊ 0⤋
umm... did you take off some clothes in the elevator??.. haha
actually you should be heavier because you are closer to the earth's gravitational pull, or do you mean when you are actually riding the elevator. then this is because the ground is falling so your body is slightly behind it causing you to be, to an extent, free falling... so you should be slightly lighter in that case
2006-09-20 20:30:58 · answer #4 · answered by Anonymous · 0⤊ 0⤋
falling down you are going with the pull of gravity so it is lessened on your body, and you would not push on the scale as hard as if standing still. it's like freefall in a plane going toward the ground where you float for a while. going up you go against gravity and the pull of gravity on your body in increased. like in a plane going up. hope that made sense
2006-09-20 20:36:45 · answer #5 · answered by foxfirevigil 4 · 0⤊ 0⤋
Because the floor, and scales are not pushing back up on your body, giving you a smaller weight.
2006-09-20 20:30:06 · answer #6 · answered by tlf 3 · 0⤊ 0⤋
Because of the air that controls the gravity.
2006-09-20 20:30:03 · answer #7 · answered by Sam X9 5 · 0⤊ 0⤋
you wouldn't weigh less in an elevator going up or down, because your mass doesn't change.
2006-09-20 20:31:10 · answer #8 · answered by Sara 6 · 0⤊ 0⤋