Download Chapter 5 Homework

Chapter 5 HW
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Problems 1, 2, 3
1.
A block of mass m1 = 250 g is at rest on a plane that makes an angle of θ = 30° with the horizontal.
The coefficient of kinetic friction between the block and the plane is 0.100. The block is attached
to a second block of mass m2 = 200 g that hangs freely by a string that passes over a frictionless,
massless pulley (Figure 5-62). When the second block has fallen 30.0 cm, what will be its speed?
2.
In Figure 5-62, m1 = 4.0 kg and the coefficient of static friction between the block and the incline
is 0.40. (a) Find the range of possible values for m2 for which the system will be in static
equilibrium. (b) Find the frictional force on the 4.0-kg block if m2 = 1.0 kg.
3.
In Figure 5-62, m1 = 40 kg, m2 = 5.0 kg, and the coefficient of kinetic friction between the inclined
plane and the 4.0-kg block is µk = 0.24. Find the magnitude of the acceleration of the masses and
the tension in the cord.
Chapter 5 HW
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4.
A 60-kg block slides along the top of a 100-kg block. The 60-kg block
2
has an acceleration of 3.0 m/s while a horizontal force of 320 N is
applied to it, as shown in Figure 5-67. There is no friction between the
100-kg block and a horizontal frictionless surface, but there is friction
between the two blocks. (a) Find the coefficient of kinetic friction
between the blocks. (b) Find the acceleration of the 100-kg block during
the time that the 60-kg block remains in contact.
5.
A 0.20-kg stone is whirled in a horizontal circle on the end of an 0.80-m-long string. The string
makes an angle of 20° with the horizontal. Determine the speed of the stone.
6.
A 0.75-kg stone attached to a string is whirled in a horizontal circle of radius 35 cm as in the
tetherball in Example 5-11. The string makes an angle of 30° with the vertical. (a) Find the speed
of the stone. (b) Find the tension in the string.
7.
An airplane is flying in a horizontal circle at a speed of 480
km/h. The plane is banked for this turn, its wings tilted at an
angle of 40° from the horizontal (Figure 5-76). Assume that a
lift force acting perpendicular to the wings acts on the aircraft as
it moves through the air. What is the radius of the circle in which
the plane is flying?
Chapter 5 HW
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8.
On a weekend archeological dig, you discover an
old club-ax that consists of a symmetrical 8.0-kg
stone attached to the end of a uniform 2.5-kg stick.
You measure the dimensions of the club-ax as
shown in Figure 5-77. How far is the center of
mass of the club-ax from the handle end of the
club-ax?
9.
Find the center of mass of the uniform sheet of plywood in
Figure 5-79. Consider this as a system of effectively two
sheets, letting one have a “negative mass” to account for the
cutout. Thus, one is a square sheet of 3.0-m edge length and
mass m1 and the second is a rectangular sheet measuring 1.0 m
x 2.0 m with a mass of -m2. Let the coordinate origin be at the
lower left corner of the sheet.
10. Two 3.0-kg particles have velocities
and
. Find the velocity of the center of mass of the system.
11. A 1500-kg car is moving westward with a speed of 20.0 m/s, and a 3000-kg truck is traveling east
with a speed of 16.0 m/s. Find the velocity of the center of mass of the car–truck system.