Test: Rest And Motion - Class 9 MCQ

Rest and motion are the relative terms because they depend on the observer’s frame of reference.
If an observer is at rest in his or her own frame of reference, but he may be moving in other observer's frame of reference. So if two different observers are not at rest with respect to each other, then they too get different results when they observe the motion or rest of a body.

In this case
Displacement = hypotenuse
Displacement = (8² +6²)^1/2 = 10 m

"Displacement will be zero because displacement is the difference between initial and final position but after one revolution the second hand came to its initial position; so it's final and initial position is same so displacement is zero "

His displacement will be zero although distance covered is non-zero since he ends up where he started.

Displacement can be zero but distance cannot be zero because distance is the total path covered but displacement is the shortest distance between the initial and final position. It can be zero at the end of one round.

Let n be the distance between a and b. Then, the total time taken would be:

n/40 + n/60

And the total distance is 2n. So:

V=distance/time=2n/ n/40 + n/60

=240n/3n+2n

=240/5

=48 m/s

60km.east + 90km.west =150km.

Non Uniform motion is defined as the motion of an object in which the object travels with varied speed and it does not cover same distance in equal time intervals, irrespective of the time interval length.

Examples:

1. If a car covers 10 meters in first two seconds, and 15 meters in next two seconds.

2. The motion of a train.

Vector quantity has both magnitude and direction but scalar quantity have only magnitude

A body whose position with respect to surrounding doesn't change is said to be in a state of rest .