Download Problems Chapter5 Q9 My Solutions

Physics 110 Problems - My Solutions
Dr. Hulan E. Jack Jr.
Chapter 5 Q 9
Griffith, W. Thomas; The physics of everyday phenomena: a conceptual introduction for
physics;4th Edition ISBN 0-07-250977-5
THE PROBLEM STATEMENT
Ch5 Q9 A car travels around a flat (nonbanked) curve with constant speed.
a. Sketch a diagram showing all of the forces acting on the car.
b. What is the direction of the net force acting on the car? Explain.
YOU TRY IT HERE FIRST !!!
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Physics 110 Problems - My Solutions
Dr. Hulan E. Jack Jr.
Ch5 Q9 A car travels around a flat (nonbanked) curve with constant speed.
a. Sketch a diagram showing all of the forces acting on the car.
b. What is the direction of the net force acting on the car? Explain.
Definitions, concepts , principles
a concept
Any curve is a part of a circle of “curvature” R of that curve. So, for clarity let’s sketch a circle
that has the curvature R at this instant. Then proceed with the problem.
Definitions and priciples
An object traveling on a circular path of radius R at a constant speed v has an centripetal
acceleration, ac, where ,
ac = v2/R
and ac is a vector pointing towards the center of the circle while the velocity v has constant
magnitude and always tangent to the circle.
mcar v
car
car
ac
R
R
O
v into the paper
mcar
ac = vcar2/R
unbanked road
R
Discu
ssion
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O
center of circle
Physics 110 Problems - My Solutions
Dr. Hulan E. Jack Jr.
Ch5 Q9 A car travels around a flat (nonbanked) curve with constant speed.
a. Sketch a diagram showing all of the forces acting on the car.
b. What is the direction of the net force acting on the car? Explain.
Basic Solution (Minimum Expected from the student)
a.
v into the paper
ac = vcar2/R
mcar
W=mg
road pushes car up
N
Fs
road pushes car towards center.
R (radius)
O
center of circle
b.
For circular motion around a circular path of radius R, the acceleration points towards
the center of that circle. By Newton’s 2nd Law of Motion, Fnet = ma , the net force acts in the
same direction of the acceleration. Hence Fnet points towards the center of the circle.
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