Important Points: Motion & Time | Science Class 7 PDF Download

Important Points:

Motion: When an object changes its position with elapse of time in respect to a stationary object, such as a building, electric pole, etc., the object is said to be in motion.

Slow and Fast Motion: If an object A covers more distance and object B covers less distance in same time, then object A is called in Fast Motion and object B is called in Slow Motion.

Rectilinear Motion: Motion along a straight line is known as RECTILINEAR MOTION OR MOTION ALONG A STRAIGHT LINE.

Curvilinear Motion: Motion along a curve line is known as CURVILINEAR MOTION.

Circular Motion: Motion along a circle is known as CIRCULAR MOTION.

Speed: Distance covered by an object in unit time is called speed. This means Speed is equal to Distance upon Time.

Uniform Speed: If an object covers a fixed distance in each unit of time the motion is known as UNIFORM MOTION or UNIFORM SPEED.

Non-uniform Speed: If an object does not cover a fixed distance in each unit of time the motion is known as NON-UNIFORM MOTION or NON-UNIFORM SPEED.

Average Speed: Total distance covered divided by total time taken is known as AVERAGE SPEED.

Periodic Motion or Oscillatory Motion: When an object repeats its motion after every fixed interval of time, the motion of the object is called PERIODIC MOTION OR OSCILLATORY MOTION.

Oscillation: The motion of pendulum starting from one extreme end to another extreme end and back to the first extreme end is called one oscillation.

Time Period: Time taken to complete one oscillation by the pendulum is called time period.

Unit of Time: Time is measured in second.

Unit of speed: Unit of speed is meter/second (m/s).

Speedometer: A device used to measure the speed of a vehicle is called SPEEDOMETER.

Odometer: A device used to measure the distance covered by a vehicle.

Distance time graph of a moving vehicle with a constant speed is a straight slanting line. Speed-time graph for the same vehicle will be a straight line parallel to x-axis.