in the elevator (but nor standing on the scale), and in some of the cases below,
ID: 1874578 • Letter: I
Question
in the elevator (but nor standing on the scale), and in some of the cases below, the friend applies downward force on you 3. You (mass 650 kg) are standing on a "bathroom scale" while riding in an elevator. A friend is an upward or reads the magniamde of the normal force of the floor on yow. For the following questions that ask for a "scale reading."please provide normalfo ss ts pts.) The elevator is ascending at constant speed of 100 m/'s, and your friend is not touching you. What is the reading on the scale? Show your work. b. (4 pts) On a completely different elevator ride: The elevator has a constant upward acceleration of 0.750 m/s your nearby friend also simultaneously pushes vertically downward on your shoulders with 120. N of force. What is the reading on the scale? Show your work. e. (3 pts.) On yet another completely different elevator ride: At a time when the scale reading is 555 N, and your friend is nor touching you, what are the magnitude and direction of the elevator's acceleration? Show your work. BONUS: (+l pt.) In the scenario described in part (c), the elevator... A. is speeding up B. is slowing downC.could be either speeding up or slowing down BONUS: (+I pt.) The elevator cable snaps, and the elevator (and all of its contents) fall freely If your friend is not touching you during this time, what is the reading on the scale? instead of and what assumptions have they made?) ght question INOT for credit): How is it possible that some scales are labeled in kilograms (mass unis) newtons or pounds (force units)? What calculation or conversion has the scale manufacturer performedExplanation / Answer
solution:
your mass , m = 65kg
weight = mg = 65x9.8 = 637 N
a) if the elevator moving upwards with constant speed 1m/s
then the scale reading will show your actual weight = 637 N
b) if the acceleration = 0.75m/s^2
Fy = ma
N + (-w-Ff) =ma
N-w-Ff = ma
N = ma +w+Ff = 65*0.75 + 637 + 120 = 805.75 N upwards
c) scale reading = 555 N
acceleration = ??
accelerating downwards: because the normal force is less than the actual weight (555<637)
555 - 637 = ma
-82 = ma
a = - 1.26 m/s^2
the magnitude of acceleration is 1.26m/s^2 and direction would be downwards
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