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question 9 on the practice quiz of physics fundamentals mechanics lesson 5

 
 
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question 9 on the practice quiz of physics fundamentals mechanics lesson 5
by Jialin Wang - Saturday, January 22, 2022, 10:47 PM
 

It asks:

The 42 kg man in the roller coaster car is sitting on a bathroom scale. If he is traveling at 37.6 m/s at exactly halfway up the loop and the radius of the vertical coaster track is 79 meters, to the nearest newton what does the scale read?


For this one  I did some calculations and found that the net force is mv^2/r=752N, which is the correct answer. I thought that the 752N represents the red arrow(net force).

 If I stopped here I should've got this question right, but I did another step since there is gravity(blue arrow) acting on it so I did some trig and find what the normal force should be:629N (the green arrow).

Which should be shown in the bathroom scale, but actually the bathroom scale shows the net force(red arrow) instead of the normal force(green arrow) in this situation. I am confused about whether I should include gravity(blue arrow) or not because the acceleration and gravity are perpendicular.