Important Questions Answer from Motion and Time Class 7 Science

Class 7 Science Motion and Time

What is motion?

The motion of an object is defined as the change in its position with respect to time. When the position of an object does not change with respect to time, the object is said to be at rest or stationary. 

What is the difference between uniform and non-uniform motion?

The differences are-

Uniform motion

1. It is a type of motion wherein the object moves in a straight line. Its velocity remains unchanged along that straight line, irrespective of the time duration. It occupies equal distances at equal time intervals.
2. Uniform motion has zero acceleration.
3. The uniform motion and the actual speed of the object are identical.
4. The equal distance at an equal interval of time.
5. The distance to time graph is a straight line.

Non-uniform motion

1. Contrary to Uniform motion, Non-Uniform Motion is a type of motion wherein the object moves at different speeds and does not cover the same distance at equal time intervals, irrespective of the duration of the time interval.
2. The non-uniform motion has non-zero acceleration.
3. The non-uniform motion varies from the object’s actual speed.
4. Unequal distances at equal intervals of time.
5. The distance to time graph shows a curved line.

 What is speed? State its SI unit

Speed is defined as the rate of change of an object’s position with time. For example. For example, the speed of a car is calculated by taking into account the distance that the car travels in a certain amount of time.

Therefore, the SI unit of speed is meters per second (m/s). Speed is also measured in kilometers per hour (km/h). 

What are quartz clocks?

Quartz clocks are clock mechanisms that use quartz crystals to calculate time. They are also called electronic clocks and watches. The mechanisms of a quartz clock depend on the electric field of a quartz crystal. When a quartz crystal is placed in an electronic circuit, the interaction between the mechanical stress and the electrical field causes the crystal to vibrate. This generates a constant electric signal which is used to measure time.

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