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PROBLEM 18.50
Determine the kinetic energy imparted to the cube of Problem
18.21.
PROBLEM 18.21 One of the sculptures displayed on a
university campus consists of a hollow cube made of six
aluminum sheets, each 1.5 1.5 m,
welded together and
reinforced with internal braces of negligible weight. The cube is
mounted on a fixed base at A and can rotate freely about its
vertical diagonal AB. As she passes by this display on the way
to a class in mechanics, an engineering student grabs corner C
of the cube and pushes it for 1.2 s in a direction perpendicular
to the plane ABC with an average force of 50 N. Having
observed that it takes 5 s for the cube to complete one full
revolution, she flips out her calculator and proceeds to
determine the mass of the cube. What is the result of her
calculation? (Hint: The perpendicular distance from the diagonal
joining two vertices of a cube to any of its other six vertices can
be obtained by multiplying the side of the cube by 2/3.)
PROBLEM 18.50 (Continued)
PROBLEM 18.51
Determine the kinetic energy lost when edge C of the plate of Problem 18.29
hits the obstruction.
PROBLEM 18.52
Determine the kinetic energy lost when the plate of Problem 18.31
hits the obstruction at B.
PROBLEM 18.52 (Continued)
PROBLEM 18.53
Determine the kinetic energy of the space probe of Problem 18.33 in its motion about its mass center after its
collision with the meteorite.
PROBLEM 18.53 (Continued)
PROBLEM 18.54
Determine the kinetic energy of the space probe of Problem 18.34 in its motion about its mass center after its
collision with the meteorite.
PROBLEM 18.54 (Continued)
PROBLEM 18.55
Determine the rate of change G
H
of the angular momentum G
H of the
disk of Problem 18.1.
PROBLEM 18.1 A thin, homogeneous disk of mass m and radius r spins
at the constant rate 1
about an axle held by a fork-ended vertical rod,
which rotates at the constant rate 2.
Determine the angular momentum
G
H of the disk about its mass center G.
