 # Motion and Time Class 7 Science Notes - Chapter 13

Speed is defined as the distance traveled by an object per unit time. It helps us to know which object is leading or to analyze which object is traveling faster when compared to other objects. Speed can be mathematically defined as the distance traveled by an object divided by the time taken by the object to cover the distance.

Speed = Distance / Time

The basic unit to measure speed is meter per second. Time can be measured with periodic events such as a periodic motion of the pendulum. This is used in watches and clocks. We can represent motion in a pictorial form by the distance-time graph. When an object is moving with at a constant speed, the distance-time graph is a straight line.

### Motion and Time Class 7 Extra Questions

1. What is the unit used to measure the speed of the train?
2. What is the unit to measure time?
3. A car travels at a speed of 40 km/h for 15 minutes and for the next 15 minutes it travels at a speed of 60 km/h. What is the total distance traveled by car?
4. Time taken by Salim on a bicycle to reach the school from the house is 15 minutes. The speed of the bicycle is given as 2 m/s. What is the distance between his house and school?
5. Time taken by a train to cover a distance of 240 km is 4 hours. What is the speed of the train?
6. State true or false –
1. The unit of time is kg.
2. The unit to measure the distance between two points is Kilometer.
3. All objects move at a constant speed.

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