Download Problems Chapter4 Q14 My Solutions

Physics 110 Problems - My Solutions
Dr. Hulan E. Jack Jr.
Chapter4 Q14
Griffith, W. Thomas; The physics of everyday phenomena: a conceptual introduction for
physics;4th Edition ISBN 0-07-250977-5
THE PROBLEM STATEMENT
Ch4 Q14 A car goes around a curve traveling at constant speed.
a. Is the acceleration of the car zero in this process? Explain.
b. Is there a non-zero total force acting on the car? Explain.
YOU TRY IT HERE FIRST !!!
Page 1 of 3
Physics 110 Problems - My Solutions
Dr. Hulan E. Jack Jr.
Ch4 Q14 A car goes around a curve traveling at constant speed.
a. Is the acceleration of the car zero in this process? Explain.
b. Is there a non-zero total force acting on the car? Explain.
Definitions, concepts , principles
a.
velocity is the time rate of change of displacement.
velocity v =
change in displacement
Δd
=
changein time
Δt
b.
c.
velocity is a vector.
A vector is described by a magnitude and a direction.
d.
Newton’s 2nd Law of Motion
F=ma
Discussion
a.
b.
c.
The direction the car travels is the
direction that the car’s front points.
The direction that the car’s front
points is the direction of the velocity.
As the car travels around the circular
track the direction that its front points
changes.
Page 2 of 3
Physics 110 Problems - My Solutions
Dr. Hulan E. Jack Jr.
Basic Solution (Minimum Expected from the student)
Ch4 Q14 A car goes around a curve traveling at constant speed.
a. Is the acceleration of the car zero in this process? Explain.
b. Is there a non-zero total force acting on the car? Explain.
a.
No! While the magnitude of this velocity is constant, its direction of the velocity vector is
constantly changing. Any change in velocity produces an acceleration. Hence , the car
has a non-zero acceleration.
It is centripetal acceleration, ac =v2/R ,
where v is the velocity and R is the radius of the circle.
b.
Yes! From Newton’s 2nd Law of Motion, F= ma, there must be a force causing the
acceleration.
It is the centripetal force
F= m v2/R
Page 3 of 3