Chapter 6
Mechanical Energy
Kinetic
Energy is the energy of motion of any moving object.
The
Work-Energy Theorem:
Example
6
A
4.1 kg box of books is lifted vertically from rest a distance
of 1.6 m by an upward applied force of 60.0 N. Find (a) the work
done by the applied force, (b) the work done by gravity, and
(c) the final speed of the box.
Solution
Example
7
The
figure shows two industrial spies sliding an initially stationary
225 kg floor safe a displacement of
magnitude 8.50 m, straight toward their truck. The push of
Spy 001 is 12.0 N, directed at an angle of downward
from the horizontal: the pull of
Spy 002 is 10.0 N, directed at above
the horizontal. The magnitudes and directions
of these forces do not change as the safe moves, and the floor
and safe make frictionless contact. (a) What is the net work
done on the safe by forces and during
the displacement ?
(b) During the displacement, what is the work
done
on the safe by the gravitational force and
what is the work done
on the safe by the normal force from
the floor? (c) The safe is initially stationary. What is its
speed at
the end of the 8.50 m displacement?
Solution
Mechanical Energy Part 2 |