Elevator Motion


Scale Reading


(This is the normal force!)

Net F




Direction of F and a

(up, down, zero)

Scale Reading

(more, less, weight)

1.  At Rest

Going Down

2.  Speeding up at top

3.  Constant speed downward

4.  Slowing down at bottom

Going Up

5.  Speed up at bottom

6.  Constant speed upward

7.  Slow down at top

8.  Cable Breaks

1.  Draw a free-body diagram for a person standing on a scale in the elevator:  a)  at rest; b) accelerating upward; c) accelerating downward; d) moving at a constant velocity upward or downward.

2.  Fill in the first two columns (your hypothesis).

3.  Write the scale readings in pounds in the table when we ride the elevator.  Convert these to Newtons (1 lb=4.45 N).

4.  Record the persons’s weight on your free-body diagram.

5.  Compute the net force for each part of the elevator ride.

6.  Compute the person’s mass.  Remember that weight in Newtons is mass in kg times 9.8!

7.  Find the person’s acceleration.  (Use F=ma.)

8.  Write a few sentences that answer the following:  If you wake up in an elevator and there are no windows or lights, can you tell if you are moving or not?  How?

Mary Norris                Questions or comments?  mnorris@vt.edu