Question

1.
SHORT ANSWER QUESTIONS
When is an object said to be in motion?
Name the two kinds of motion that the Earth has.
3.
Name the two inventions that brought about revolution in the field of transport
Why do we need standard units for measurement?
2.
4.​

Answer 1

Answer:

a object is said to be in motion when it is applying force or moving

gravitational and frictional force

Answer 2

Answer:

1. An object is said to be in motion if it changes its position with time,with respect to its surroundings.
2. Rotation and Revolution.
3. Steam engine and Wheel
4. We need standard unit for measurement to make our judgement more reliable and accurate. For proper dealing, measurement should be same for everybody. Thus there should be uniformity in measurement. For the sake of uniformity we need a common set of units of measurement, which are called standard units.