• Support PF! Buy your school textbooks, materials and every day products Here!

Find the apparent weight

  • #1
73
3

Homework Statement


A car traveling on a straight road at 9.15m/s goes over a hump in the road. The hump may be regarded as an arc of a circle of radius 10.4m. What is the apparent weight of a 665N woman in the car as she rides over the hump?

Homework Equations



##F=ma##; ##a=v^2/r##

The Attempt at a Solution



At the top of the bump the woman will experience a centripetal acceleration towards the center of the arc (i.e. downwards). The magnitude of this acceleration is ##v^2/r=8.05m/s^2##. The total downwards acceleration of the woman is hence ##9.8+8.05=17.05m/s^2##. Her true weight is ##665/9.8=67.86kg##. So, her apparent weight is ##67.86*17.05=1156.96N##. Does this sound correct?
 

Answers and Replies

  • #2
BvU
Science Advisor
Homework Helper
2019 Award
13,039
3,016
Simple quesstion, simple answer: no.
Are you presseed doen in your seat at the top of a bump, or almost flying up ?
 
  • #3
73
3
Simple quesstion, simple answer: no.
Are you presseed doen in your seat at the top of a bump, or almost flying up ?
Almost flying up; where is the problem in my analysis of the problem?
 
  • #4
BvU
Science Advisor
Homework Helper
2019 Award
13,039
3,016
Where does the centripetal force come from ?
 
  • #5
kuruman
Science Advisor
Homework Helper
Insights Author
Gold Member
8,726
2,129
I should add that the apparent weight of the woman is not constant as the car goes over the hump. Usually one does this sort of calculation when the car is at the top of the hump and the instantaneous velocity is horizontal.
 
  • #6
ehild
Homework Helper
15,427
1,824
Almost flying up; where is the problem in my analysis of the problem?
The problem is your result: that the woman feels much heavier on the bump then on flat gound, instead of as if flying away.
 
  • #7
Why you don't make a plot with all the forces applied on the women, (at the top of the hump), and then you identify which of them is the apparent weight
 
Last edited:

Related Threads on Find the apparent weight

Replies
6
Views
15K
  • Last Post
Replies
2
Views
10K
  • Last Post
Replies
12
Views
2K
  • Last Post
Replies
1
Views
1K
Replies
17
Views
17K
  • Last Post
Replies
6
Views
2K
  • Last Post
Replies
1
Views
2K
  • Last Post
Replies
1
Views
465
  • Last Post
Replies
6
Views
40K
  • Last Post
Replies
2
Views
1K
Top