Transcript Slide 1

CT1: When I whirl a ball in a vertical
circle attached to a rubber band, which
statement is true?
A. The rubber band will contract to
provide an outward force on the nurf
ball.
B. The rubber band will contract because
of the inward force on the nurf ball.
C. The rubber band will not change in
length.
D. The rubber band will stretch because
of the outward force on the nurf ball.
E. The rubber band will stretch to provide
an inward force on the nurf ball.
CT2
A.
B.
C.
D.
Chapter 6 Circular Motion and Other
Applications of Newton’s Laws
6.1 Newton’s Second Law for a Particle in
Uniform Circular Motion
ar = vt2/r
Fr = mar = mvt2/r taking inward as positive
Note: ar = ac = centripetal acceleration
at =0, but because it is  to ar, it has no
bearing on the radial direction
P6.1 (p.155)
P6.55 (p.160)
CT3
A.
B.
C.
D.
E.
F.
Chapter 6 Circular Motion and Other
Applications of Newton’s Laws
6.1 Newton’s Second Law for a Particle in
Uniform Circular Motion
Comparison of Linear and Circular Motion
Chapter 6 Circular Motion and Other
Applications of Newton’s Laws
6.2 Nonuniform Circular Motion
Fr = mar = mvt2/r taking inward as positive
Ft = mat
Note: at = tangential or  acceleration

Because at is  to ar, they have no bearing on
each other’s motion. You can do two separate
1D problems (Ch.2).
CT4: At the top of the path when I whirl a
bucket of water over my head, the water in
the bucket will
A. stay in the bucket because it is forced
outward and stopped by the bottom of the
bucket.
B. stay in the bucket because gravity is
temporarily suspended.
C. stay in the bucket only if I whirl the bucket
with enough speed so that the bottom of the
bucket must supply an inward force.
D. stay in the bucket at any speed that I whirl
the bucket.
E. not stay in the bucket.
P6.58 (p.161)
r
rsin
Chapter 6 Circular Motion and Other Applications of
Newton’s Laws
6.4 Motion in the Presence of Resistive Forces
A. Smaller objects, lower speed: R = bv
B. Larger objects, higher speeds: R = DAv2/2
D = drag coefficient;  = fluid density;
A = cross-sectional area
Both forces oppose motion.
P6.27 (p.157)
Bs = 0.750
Bk = 0.640
Ps = 0.520
Pk = 0.450
Fig. P6.60, p.178