HPHY 154 Workout 07c
Applications of Newton’s Laws of Motion
Prof. A. E. Bak
Name
1.
S&J Problem 69 (formerly S&B Problem 613). Consider a conical pendulum with an 80.0
kg
bob on a 10.0
m
wire making an angle of
!
!
5.00
!
with the vertical as shown in Figure
P
6.9
(on page 172).
a.
Determine the horizontal and vertical components of the force exerted by the wire on the
bob.
b.
Find the radial acceleration of the bob.
2.
S&J Problem 619 (formerly S&B Problem 621). A rollercoaster car has a mass of 500
kg
when fully loaded with passengers. See Figure
P
6.19 on page 173.
a.
If the car has a speed of 20.0
m
/
s
at point
A
, then what is the force exerted by the track on
the car at that point?
b.
What is the maximum speed the car can have at point
B
and still remain on the track?
3.
A circular curve of banked highway is designed for traffic moving at 60
km
/
h
. That is, there is
no static friction between tires and road at that speed.
a.
If the radius of the curve is 150
m
, then what is the correct banking angle of the road?
b.
If the curve were not banked, then what would be the minimum coefficient of static friction
between tires and road that would allow cars to negotiate the curve without sliding off the
road?
4.
S&J Problem 667 (formerly S&B Problem 666). A car rounds a banked curve as shown in
Figure 6.6 (on page 155). The road’s radius of curvature is
R
, the banking angle is
!
, and the
relevant coefficient of static friction is
"
s
.
a.
Determine the range of speeds the car can have without slipping up or down the banked
surface.
b.
Find the value for
"
s
for which the minimum safe speed is zero.
c.
What is the range of speeds possible for the slippery conditions of
R
!
100
m
,
!
!
10.0
!
,
and
"
s
!
0.100?
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 Spring '08
 stevens
 Force, Friction, Mass, Work, Tan

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