# Elevator acceleration with mass

Woman stand on a scale in a moving elevator. Her mas is 60 kg, and combined mass of elevator and scale is additional 815 kg. From rest, elevator accelerates upwards. During Acceleration, the cable applies a force of 9410N. What does the scale read during acceleration. Formula or solution would be appreciated. Thanks.

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Tom Mattson
Staff Emeritus
Gold Member

Well I know F=mass*acceleration. So 9410= 875*A. A=10.754. I dont really know what the weight of the scale would read though at that time.

Tom Mattson
Staff Emeritus
Gold Member
tennisman03110 said:
Well I know F=mass*acceleration. So 9410= 875*A. A=10.754.
You need to avoid the urge to plug numbers into equations without thinking about what it is that you are doing. Newton's second law says that the net force on an object is equal to the product of its mass and acceleration. The force exerted by the cable is not the net force on the elevator. You were given 3 weights, and you need to include them in your analysis.

You should start every single one of these problems by drawing a free body diagram, and then by applying Newton's 2nd law.

I dont really know what the weight of the scale would read though at that time.
Hint: If you're standing on a scale, it doesn't read your weight, but rather the normal force applied to you.

I dont really understand what the normal force would be. IS it 9410. If so then the weight would equal 9410 with no acceleration. I can't really figure out what to do to find this though, becasue their is acceleration and a lady on it.

Tom Mattson
Staff Emeritus