MOTION AND TIME
IMPORTANT TERMS
Motion: - Motion is change in position of an object over a time.
Linear Motion: - It is a motion along straight line. It is also called rectilinear motion.
Circular Motion: - Movement of an object on a circular path is called circular motion.
Periodic Motion: - It is a repeated motion which occurs at regular interval of time.
Speed: - The distance covered by an object in unit time is called speed.
Uniform Motion: - It is a kind of motion in which a body covers equal distance in equal intervals of time.
Non Uniform Motion: - It is a kind of motion in which a body covers variable distance in equal intervals of time.
Speedometer: - It is a device which measures speed and displays instantaneous speed of a vehicle.
Odometer: - It is an instrument which measures speed travelled by a wheeled vehicle between two intervals of time.
MOTION
Motion is described as change in position of an object over time. The position of some objects with respect to its surroundings doesn’t change with time. Such objects are said to be at rest. If a body moves with more speed the motion of body is said be fast e.g., motion of train. On the other hand if a body moves with less speed, the motion is said to be slow e.g. movement of an ant.
TYPES OF MOTION
Linear Motion
It is movement of an object along a straight path. It is also called rectilinear motion e.g. motion of a car along a straight line.
Circular Motion
It is movement of an object along a circular path. Movement of planet on its orbit around the sun is an example of circular motion.
Periodic Motion
Periodic motion is a motion that repeats itself at regular interval of time e.g, Motion of the pendulum of a clock, motion of planets around the Sun etc.
Oscillatory Motion
A to and fro or back and forth motion of a body along the same path, without any change in shape of the body is called an oscillatory motion.
Random Motion
When the objects do not move along a definite path, it is called random motion e.g. roaming of butterfly on flower.
ANCIENT TIME MEASURING DEVICES
The earliest method of measuring time was through observation of celestial bodies. Sun dials, Water clocks and Sand dials were used to measure time in ancient time.
MEASUREMENT OF TIME
Clocks or watches are used to measure time.
SPEED
It is defined as distance covered by an object in unit time.
Speed =Distance/Time
Or, Distance = Speed X Time
UNIFORM SPEED
If an object covers equal distance in equal interval of time, the object is said to be in uniform speed or uniform motion.
NON UNIFORM SPEED
If an object covers unequal distances in equal interval of time, the object is said to be in non-uniform speed or non-uniform motion.
VELOCITY
It is speed in a particular direction.
AVERAGE SPEED
It is defined as total distance covered divided by total time taken.
UNIT OF DISTANCE
The base unit of length in the International System of Units (SI) is metre. The SI unit symbol is ‘m’.
UNIT OF TIME
The second is the base unit of time in the International System of Units (SI). Abbreviation of second is ‘s or sec’. The SI unit symbol is ‘s’.
UNIT OF SPEED
SI unit of speed is metre per second (m/s or ms-1‑). Unit of velocity and speed is same.
SIMPLE PENDULUM
A simple pendulum consists of a bob hanging at the end of a string. The time taken by the pendulum to complete one oscillation is called its time period. The motion of pendulum starting from one extreme end to another extreme end and back to the first extreme end is called one oscillation.
GRAPH
It is used to study the relation between two variable physical quantities. In a graph, X-axis (horizontal axis) represents independent variable while Y-axis (vertical axis) represents dependent variable. The graph may be straight or curved line.
DISTANCE TIME GRAPH
Distance-time graph is the plot of distance travelled by an object against time. If the distance time graph is straight line then the object is moving with uniform speed. A curved line graph between distance and time indicates that the object is moving with non uniform speed.
INTERESTING FACTS
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