## Grade 6  |   Science  |   Types of motion, Motion and Measurement of Distances, Olympiad, CBSE, ICSE, SOF, ITO

### Types of motion

• Rectilinear motion: When an object moves in a straight line, the motion is known as rectilinear motion. All points on the object move in straight lines along parallel paths. E.g. A ball dropped from a height, a car racing on a straight track etc.
• Translatory motion: When all points on the body of the object move the same distance in the same interval of time, the object is said to be moving in translatory motion. Rectilinear motion is translatory motion. Another type of translatory motion is curvilinear motion. E.g. A car moving on a road, a ball sliding on a path or a ball rolling on an inclined plane.

Imp concept: Rolling is translatory as well as rotatory motion. Sliding is only translatory motion.

• Random motion: When the direction of motion of the object is not fixed and keeps on changing, the motion is known as random motion.
• Curvilinear motion: When a body moves along a circular path, it is said to be moving in curvilinear motion. E.g. a stone thrown high at an angle to the ground, the path of a javelin.
• Circular motion: When a body moves in a circular path, it is known as circular motion. At any point in time during the motion, the distance between the body and the center of the path remains same. E.g. revolution of the earth, car moving along a round-about.
• Rotatory motion: The motion of an object along its axis such that all points on the object move in a circular path with the centers on the axis. E.g. rotation of the earth, a fidget spinner, a rotating fan or a spinning top.
• Periodic motion: The motion which is repeated after a fixed interval of time is known as periodic motion. E.g. Rotation and revolution of the earth. Rotation of clock hands, pendular of a clock etc.
• Oscillatory motion: It is also known a vibratory motion. In this motion object moves to and fro about a mean position. E.g. movement of the bob of a pendulum, strings of a guitar, rocking chair etc. Oscillatory motions are often periodic.

Imp concepts:

• Rectilinear motion can be uniform or non-uniform. It means moving in a straight line.
• A periodic motion need not be oscillatory E.g. rotation of the earth.
• Rotatory and circular motions are different. In rotatory object turns along its axis but in circulatory motion, an object moves along a circular path such that its distance from the center of the path is always constant throughout the motion.