A pitcher throws a 0.142-kg baseball at 47.2 m/s. As it travels 16.8 m to home plate, the ball slows down to 42.5 m/s because of air resistance. Find the change in temperature of the air through which it passes. To find the greatest possible temperature change, you may make the following assumptions. Air has a molar specific heat of C P = 7 2 I R and an equivalent molar mass of 28.9 g/mol. The process is so rapid that the cover of the baseball acts as thermal insulation and the temperature of the ball itself does not change. A change in temperature happens initially only for the air in a cylinder 16.8 m in length and 3.70 cm in radius. This air is initially at 20.0°C.
A pitcher throws a 0.142-kg baseball at 47.2 m/s. As it travels 16.8 m to home plate, the ball slows down to 42.5 m/s because of air resistance. Find the change in temperature of the air through which it passes. To find the greatest possible temperature change, you may make the following assumptions. Air has a molar specific heat of C P = 7 2 I R and an equivalent molar mass of 28.9 g/mol. The process is so rapid that the cover of the baseball acts as thermal insulation and the temperature of the ball itself does not change. A change in temperature happens initially only for the air in a cylinder 16.8 m in length and 3.70 cm in radius. This air is initially at 20.0°C.
Solution Summary: The author explains the formula to determine the change in temperature of the air through which it passes.
A pitcher throws a 0.142-kg baseball at 47.2 m/s. As it travels 16.8 m to home plate, the ball slows down to 42.5 m/s because of air resistance. Find the change in temperature of the air through which it passes. To find the greatest possible temperature change, you may make the following assumptions. Air has a molar specific heat of CP =
7
2
I
R and an equivalent molar mass of 28.9 g/mol. The process is so rapid that the cover of the baseball acts as thermal insulation and the temperature of the ball itself does not change. A change in temperature happens initially only for the air in a cylinder 16.8 m in length and 3.70 cm in radius. This air is initially at 20.0°C.
5.48 ⚫ A flat (unbanked) curve on a highway has a radius of 170.0 m.
A car rounds the curve at a speed of 25.0 m/s. (a) What is the minimum
coefficient of static friction that will prevent sliding? (b) Suppose that the
highway is icy and the coefficient of static friction between the tires and
pavement is only one-third of what you found in part (a). What should
be the maximum speed of the car so that it can round the curve safely?
5.77 A block with mass m₁ is placed on an inclined plane with
slope angle a and is connected to a hanging block with mass m₂ by a
cord passing over a small, frictionless pulley (Fig. P5.74). The coef-
ficient of static friction is μs, and the coefficient of kinetic friction is
Mk. (a) Find the value of m₂ for which the block of mass m₁ moves up
the plane at constant speed once it is set in motion. (b) Find the value
of m2 for which the block of mass m₁ moves down the plane at constant
speed once it is set in motion. (c) For what range of values of m₂ will
the blocks remain at rest if they are released from rest?
5.78 .. DATA BIO The Flying Leap of a Flea. High-speed motion
pictures (3500 frames/second) of a jumping 210 μg flea yielded the
data to plot the flea's acceleration as a function of time, as shown in
Fig. P5.78. (See "The Flying Leap of the Flea," by M. Rothschild et al.,
Scientific American, November 1973.) This flea was about 2 mm long
and jumped at a nearly vertical takeoff angle. Using the graph, (a) find
the initial net external force on the flea. How does it compare to the
flea's weight? (b) Find the maximum net external force on this jump-
ing flea. When does this maximum force occur? (c) Use the graph to
find the flea's maximum speed.
Figure P5.78
150
a/g
100
50
1.0
1.5
0.5
Time (ms)
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