Motion in Two and Three Dimensions
Need Help on a Physics Assignment, Email us or call us at 1-617-275-8164
 |
Relative Motion: |
 |
| |
An object is in motion when an object changes its position relative to a reference point or as
observed by a person. For example, an automobile is moving with respect to the ground. The
distance it goes in a period of time is called its speed and if it is in a particular direction then it is
called velocity. The change in velocity is called its acceleration.
Now, we realize that all motion is
with respect to some reference point or an observer. For example, when we see a car is driven by,
then it is moving with respect to us. When we are in a car and we see another car moving ahead of
us, then we see that the other car is moving with a greater speed with respect to ours. This type of
movement can be called relative movement. Thus, when an object moves with respect to the other
so that there is a relative velocity in between then the motion is called relative
motion.
The relative velocity is the velocity of an object with respect to the other. It is not the velocity of a
particular object in an isolated manner. To find the relative velocity we require an intermediate
reference frame. It is described as follows:
To describe the motion of object A
with respect to object O, when we know how each is
moving with respect to object B, we use the following equation involving vectors and vector
addition:
Let A has velocity VA and B moves
with velocity VB, and each velocity is given with respect to the
ground. We call the velocity VA / B the relative velocity of
A with respect to B. Then we can write
To find VA / B we can simply rearrange this equation to obtain:
Similarly the acceleration is given by,
aA/B = aA - aB
|
|
 |
|
 |
Submit your homework or assignment.
