# Apparently an easy Dynamics question

During a high-speed chase, a 2400-lb sports car traveling
at a speed of 100 mi/h just loses contact with the road as it
reaches the crest A of a hill. a) Determine the radius of
curvature r of the vertical profile of the road at A. b)
Using the value of r found in a part a), determine the
force exerted on a 160-lb driver by the seat of his 3100-lb
car as the car, traveling at a constant speed of 50 mi/h,
passes through A.

## Homework Equations

an= v^2/p, p is what we are searching from, but it if we are not given an equation of the hill, it seems unlikely that it can be solved.
p can also be found using derivatives of the position function...

Is this even solve-able?

#### Attachments

• Dynamicstest2.png
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## Answers and Replies

tiny-tim
Science Advisor
Homework Helper
hi there, fluffypuffin! welcome to pf! (try using the X2 and X2 icons just above the Reply box )
an= v^2/p, p is what we are searching from

contact is lost when the reaction force is zero …

so do F = ma for the driver, using your centripetal acceleration formula …

what do you get? You'd have to make some conversions because velocity is in seconds. So
100 mi/h= 146.6 ft/s then
p= 146.6 ^2/ 32.2

Correct?

Thank you so much!

tiny-tim
Science Advisor
Homework Helper
looks good! (are you ok on the other parts?)

Nope! Want to help me? :)

if we sum the forces in the normal direction
wouldn't it be:
mg- N= m (50)^2/ 668.04

??

tiny-tim
Science Advisor
Homework Helper
mg- N= m (50)^2/ 668.04

yes (except you need to convert the 50 into ft/s )