 #1
TRB8985
 47
 9
 Homework Statement:

At a construction site, a 65.0 kg bucket of concrete hangs from a light (but strong) cable that passes over a light, frictionfree pulley and is connected to an 80.0 kg box on a horizontal roof. The cable pulls horizontally on the box, and a 50.0 kg bag of gravel rests on top of the box.
Find the static friction force on the bag of gravel and on the box.
 Relevant Equations:
 W = mg
Good afternoon everyone,
I had a quick question on the correct way to report the answer of this problem.
I've solved it and came to the conclusion that the bag of gravel experiences no static friction, but the box experiences static friction with a magnitude equal to the weight of the bucket  637 N. This was obtained by setting up a freebody diagram on each object and setting the acceleration equal to zero, as the combined weight of the box and bag of gravel is larger than the influence of tension.
This matches the answer in my solution manual. However, I noticed something a little weird.
The author seemed to have arbitarily used three significant figures to represent the acceleration due to gravity (9.80 m/s²). There's nothing else in the problem description besides what I've provided above to indicate that we were supposed to do such a thing.
Does this mean that, when I multiply the weight of the bucket (65.0 kg) by the acceleration due to gravity (9.8 m/s²), that I have to reduce the result of exactly 637 N to an answer containing two significant figures?
i.e. 640 N?
Thank you for your help! Have a great evening and a great upcoming 2023.
I had a quick question on the correct way to report the answer of this problem.
I've solved it and came to the conclusion that the bag of gravel experiences no static friction, but the box experiences static friction with a magnitude equal to the weight of the bucket  637 N. This was obtained by setting up a freebody diagram on each object and setting the acceleration equal to zero, as the combined weight of the box and bag of gravel is larger than the influence of tension.
This matches the answer in my solution manual. However, I noticed something a little weird.
The author seemed to have arbitarily used three significant figures to represent the acceleration due to gravity (9.80 m/s²). There's nothing else in the problem description besides what I've provided above to indicate that we were supposed to do such a thing.
Does this mean that, when I multiply the weight of the bucket (65.0 kg) by the acceleration due to gravity (9.8 m/s²), that I have to reduce the result of exactly 637 N to an answer containing two significant figures?
i.e. 640 N?
Thank you for your help! Have a great evening and a great upcoming 2023.
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