Motion Flashcards
What is motion?
Motion means movement. The motion of an object is perceived when its position changes continuously with respect to some stationary object. An object may be appearing to be moving to one person and the same object may appear to be at rest for another.
What is origin?
To locate an object we have to specify or choose some suitable reference point. This reference point is called origin.
What is distance?
It is the length of the actual path travelled by the object during motion. It is a scalar quantity. During motion of an object the value of the distance canned be 0 or negative.
What is displacement?
It is the shortest distance between the initial position and final position of an object. It is a vector quantity. The displacement can be positive, 0, or negative. Between two given positions the distance travelled can never be less than the displacement.
What is uniform motion?
When an object cover equal distances in equal amounts of time, howsoever small the interval maybe, the motion of the object is said to be uniform.
What is non-uniform motion?
When an object covers equal distances in unequal amounts of time, howsoever small the intervals maybe, the motion is said to be non-uniform.
What is speed.
Speed is the rate of motion of a body. It is defined as distance travelled by the body in unit time.
Speed = Distance/Time taken or v=s/t.
The SI unit of speed is m/s or ms^-1. The speed of a body is a scalar quantity. The speed can be positive not negative.
What is uniform speed?
When a body covers equal distance in equal intervals of time
What is non uniform speed?
When a body covers unequal distance in equal intervals of time the speed of the body is said to be non-uniform. In most cases it is so. Therefore we describe the rate of motion of such bodies in terms of their average speed.
What is average speed?
The average speed of a body is obtained by dividing the total distance travelled by the total time taken.
What is velocity?
Velocity of an object is the distance travelled by a body in unit time in a given direction.
V = s/t
Its SI unit is ms^-1 or m/s
It is a vector quantity.
What is uniform velocity?
When a body covers equal distances in a particular direction in equal intervals of time it is called uniform velocity.
What is non-uniform velocity?
Non uniform velocity can be any of the following 3 ways:
1. When it covers equal distance in a particular direction in unequal intervals of time.
2. When it covers unequal distances in a particular direction in equal intervals of time.
3. When it covers equal distances in equal intervals of time, but the direction of motion changes.
What is average velocity?
When a body is moving along a straight line at variable speed, its velocity is variable, In that case we express the rate of motion of the body in terms of its average velocity.
Avg. Velocity = Initial velocity + final velocity/2
or Vavg. = u - v /2
What is acceleration?
It is the rate of change of velocity.
Acceleration = change in velocity/time
change in velocity = u - v
It is a vector quantity. Its SI unit is m/s/s or ms^-2
When a body is moving along a straight line with uniform velocity, change in velocity is 0, therefore acceleration is 0.
When the velocity of the body increases with time, then acceleration is positive. The direction of acceleration is long the direction of velocity. The motion is said to be accelerated motion.
When the velocity of a body decreases then acceleration is negative. The negative acceleration is in a direction opposite to the direction of velocity of the body. Negative acceleration is called retardation.
