Essential University Physics (3rd Edition)
3rd Edition
ISBN: 9780134202709
Author: Richard Wolfson
Publisher: PEARSON
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Textbook Question
Chapter 5, Problem 80PP
A spiral is an ice-skating position in which the skater glides on one foot with the other foot held above hip level. It’s a required element in women’s singles figure skating competition and is related to the arabesque performed in ballet. Figure 5.40 shows skater Sarah Hughes executing a spiral during her gold-medal performance at the Winter Olympics in Salt Lake City.
FIGURE 5.40 Problem 77-80
The till angle θ that the skater’s body makes with the vertical is given approximately by θ = tan−1(0.5). From this you can conclude that the skater’s centripetal acceleration has approximate magnitude
- a. 0.
- b. 0.5 m/s2.
- c. 5 m/s2.
- d. can’t be determined without knowing the skater’s speed
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Students have asked these similar questions
Problem 70. A group of three skiers stand atop a hill inclined at a steady angle of 8°. One skier uses well waxed skis
that have a coefficient of kinetic friction (with the snow) of nearly zero µK10. A second skier uses skis with a (typical)
coefficient of kinetic friction of µK2=0.04. A third skier has poorly cared for skis with a coefficient of kinetic friction of
PK3=0.1. The hill is at an elevation of 200 m above ground level. Find the speeds of each of the skiers at the bottom of
the hill.
7. ssm mmh The drawing shows a plane diving toward the ground and
then climbing back upward. During each of these motions, the lift force L
acts perpendicular to the displacement 3, which has the same magnitude,
115°
75°
(a) Dive w
(b) Climb
1.7 x 10° m, in each case. The engines of the plane exert a thrust T, which
points in the direction of the displacement and has the same magnitude
during the dive and the climb. The weight W of the plane has a magni-
tude of 5.9 × 10ʻ N. In both motions, net work is performed due to the
combined action of the forces L, T, and W. (a) Is more net work done
during the dive or the climb? Explain. (b) Find the difference between the
net work done during the dive and the climb.
A ski that is placed on snow will stick to the snow. However, when the ski is moved along the snow, the rubbing warms and partially melts the snow, reducing the coefficient of friction and promoting sliding. Waxing the ski makes it water repellent and reduces friction with the resulting layer of water. A magazine reports that a new type of plastic ski is especially water repellent and that, on a gentle 230 m slope in the Alps, a skier reduced his top-to-bottom time from 69 s with standard skis to 42 s with the new skis.
Old skis acceleration = 0.097 m/s2
New skis acceleration = 0.26 m/s2
Assuming a 3.0° slope, compute the coefficient of kinetic friction for each case.
Old skis
_______
New skis
_______
Chapter 5 Solutions
Essential University Physics (3rd Edition)
Ch. 5.1 - A roofers toolbox rests on an essentially How does...Ch. 5.2 - In the figure below weve replaced one of the hands...Ch. 5.3 - You whirl a bucket of water around in a vertical...Ch. 5.4 - The figure shows a logging vehicle pulling a...Ch. 5 - Compare the net force on a heavy trunk when its...Ch. 5 - The force of static friction acts only between...Ch. 5 - A jet plane flies at constant speed in a vertical...Ch. 5 - In cross-country skiing, skis should easily glide...Ch. 5 - Why do airplanes bank when turning?Ch. 5 - Why is it easier for a child to stand nearer the...
Ch. 5 - Gravity pulls a satellite toward Earths center. So...Ch. 5 - Explain why a car with ABS brakes can have a...Ch. 5 - A fishing line has a 20-lb breaking strength. Is...Ch. 5 - Two blocks rest on slopes of unequal angles,...Ch. 5 - Youre on a plane undergoing a banked turn, so...Ch. 5 - A backcountry skier weighing 700 N skis down a...Ch. 5 - Two forces, both in the x-y plane, act on a...Ch. 5 - Two forces act on a 3.1-kg mass that undergoes...Ch. 5 - At what angle should you tilt an air table to...Ch. 5 - A skier starts from rest at the top of a 24 slope...Ch. 5 - A tow truck is connected to a 1400-kg car by a...Ch. 5 - Studies of gymnasts show that their high rate of...Ch. 5 - Find the minimum slope angle for which the skier...Ch. 5 - Section 5.2 Multiple Objects Your 12-kg baby...Ch. 5 - If the left-hand slope in Fig. 5.30 makes a 60...Ch. 5 - Suppose the angles shown in Fig. 5.30 are 60 and...Ch. 5 - Two unfortunate climbers, roped together, are...Ch. 5 - Suppose the Moon were held in its orbit not by...Ch. 5 - Show that the force needed to keep a mass m in a...Ch. 5 - A 940-g rock is whirled in a horizontal circle at...Ch. 5 - Youre investigating a subway accident in which a...Ch. 5 - A tetherball on a 1.55-m rope is struck so that it...Ch. 5 - An airplane goes into a turn 3.6 km in radius. If...Ch. 5 - Movers slide a 73-kg file cabinet along a floor...Ch. 5 - A hockey puck is given an initial speed of 14 m/s....Ch. 5 - Starting from rest, a skier slides 100 m down a 28...Ch. 5 - A car moving at 40 km/h negotiates a 130-m-radius...Ch. 5 - Prob. 34PCh. 5 - A block is launched with initial speed 2.2 m/s up...Ch. 5 - In the process of mitosis (cell division), two...Ch. 5 - A 14.6-kg monkey hangs from the middle of a...Ch. 5 - A camper hangs a 26-kg pack between two trees...Ch. 5 - A mass m, undergoes circular motion of radius R on...Ch. 5 - Patients with severe leg breaks arc often placed...Ch. 5 - Riders on the Great American Revolution...Ch. 5 - A 45-kg skater rounds a 5.0-m-radius turn at 6.3...Ch. 5 - When a piano turns, it banks as shown in Fig. 5.35...Ch. 5 - You whirl a bucket of water in a vertical circle...Ch. 5 - A child sleds down an 8.5 slope at constant speed....Ch. 5 - The handle of a 22-kg lawnmower makes a 35 angle...Ch. 5 - Repeal Example 5.4, now assuming that the...Ch. 5 - A bat crashes into the vertical front of an...Ch. 5 - The coefficient of static friction between steel...Ch. 5 - A bug crawls outward from the center of a CD...Ch. 5 - A 310-g paperback book rests on a 1.2-kg textbook....Ch. 5 - Children sled down a41-m-long hill inclined at 25....Ch. 5 - In a typical front-wheel-drive car, 70% of the...Ch. 5 - A police officer investigating an accident...Ch. 5 - A slide inclined at 35 takes bathers into a...Ch. 5 - You try to move a heavy trunk, pushing down and...Ch. 5 - A block is shoved up a 22 slope with an initial...Ch. 5 - At the end of a factory production line, boxes...Ch. 5 - Youre in traffic court, arguing against a speeding...Ch. 5 - A space station is in the shape of a hollow ring,...Ch. 5 - In a loop-the-loop roller coaster, show that a car...Ch. 5 - Find an expression for the minimum frictional...Ch. 5 - An astronaut is training in an earthbound...Ch. 5 - You stand on a spring scale at the north pole and...Ch. 5 - Driving in thick fog on a horizontal road, you...Ch. 5 - A block is projected up an incline at angle . It...Ch. 5 - A 2.1-kg mass is connected to a spring with spring...Ch. 5 - Take k = 0.75 in Example 5.11, and plot the...Ch. 5 - Repeat the preceding problem for an arbitrary...Ch. 5 - Moving through a liquid, an object of mass m...Ch. 5 - Suppose the object in Problem 70 had an initial...Ch. 5 - A block is launched with speed v0 up a slope...Ch. 5 - A florist asks you to make a window display with...Ch. 5 - Youre al the state fair. A sideshow barker claims...Ch. 5 - One of the limiting factors in high-performance...Ch. 5 - Figure 5.39 shows an apparatus used to verify...Ch. 5 - A spiral is an ice-skating position in which the...Ch. 5 - A spiral is an ice-skating position in which the...Ch. 5 - A spiral is an ice-skating position in which the...Ch. 5 - A spiral is an ice-skating position in which the...
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