NCERT Solutions for Class 7th Science
Chapter 13. Motion and Time
- The distance covered by an object in a unit time as the speed of the object.
- If the speed of an object moving along a straight line keeps changing, its motion is said to be non-uniform.
- An object moving along a straight line with a constant speed is said to be in uniform motion.
- The time taken by the pendulum to complete one oscillation is called its time period.
- The basic unit of time is a second.
- The speedometer of a car measure Speed.
- The odometer of a car measure Distance.
- The speed is the total distance covered divided by the total time taken is called average speed.
- The time between one sunrise and the next was called a day.
- A month was measured from one new moon to the next.
- A year was fixed as the time taken by the earth to complete one revolution of the sun.
- The metallic ball is called the bob of the pendulum.
- The to and fro motion of a simple pendulum is an example of a periodic or an oscillatory
- The smallest time interval that can be measured with commonly available clocks and watches is one second.