Game Development Reference
In-Depth Information
known as a
watt
or
W
for short. A commonly used unit of power in the English system of units
is the
horsepower
or
hp
. One
hp
is equal to 745.7
W
.
Power is also used to describe the performance of engines. We will use the concept of
power when we simulate cars in Chapter 8, boats in Chapter 9, and airplanes in Chapter 10.
Summary
In this chapter, you learned about basic Newtonian mechanics—the study of forces and how
they affect the acceleration of objects. Newton's three laws of motion were introduced. Newton's
three laws will form the basis for every physical model we develop in this topic. Some of the
other things we discussed in this chapter include the following:
•
Force is a vector quantity that has both a magnitude and a direction.
•
Gravitational force is exerted by every object on every other object and is a function of
masses of the two objects and an inverse function of the square of the distance between
them.
•
Frictional force is the resistance of one object sliding over another. It is proportional to
the normal force exerted on the object and a constant known as the coefficient of friction.
•
Spring force is a variable force that is a function of the distance the spring has been
displaced from its equilibrium position.
•
A centripetal force is required for an object to travel around a curve. Centripetal force is
proportional to the square of the velocity of the object and is inversely proportional to
the radius of curvature of the object's trajectory.
•
How to develop force diagrams as an aid to physical modeling.
•
How mechanical work is a force exerted on an object over a certain distance.
•
About energy and some of the different types of energy including kinetic, potential, and
thermal energy.
•
How power is equal to an amount of work done per unit time.
Answers to Exercises
1.
Using the gravitational force equation and Newton's second law, the acceleration at the
surface of the moon is equal to
Gm
6.67
e
−
11*7.3483
e
+
22
m
a
=
moon
=
=
1.624
2
(
)
2
2
r
s
1.7374
e
+
6
moon
From this result, we see that the acceleration due to gravity on the moon is about 1/6
that found on Earth.
