An object moves with a speed of 10m/s in the positive direction. Express the speed and velocity if it is moving in opposite directionot.
Answers
Answer: speed = 10 m/s
But velocity = -10m/s
Because velocity is a vector quantity
therefore the value change when direction changes
But speed is scalar quantity so no relationship with direction
Explanation:
Answer :It is a velocity obviously.
Since speed can never be negative , this can be seen from its definition -
speed= distance travelled /time taken.
The dependency of speed on the distance travelled by the body and the time taken by it clearly shows that the speed is non - negative since neither the value of distance can be negative nor the value of time taken can be negative.
Velocity , on the other hand can be negative or positive as well as zero(0).This is because velocity is a vector quantity and we all know that it includes magnitude(as in the case of speed) as well as direction( unlike the speed which doesn't include direction).
Also it can be seen from the fact that since velocity =displacement/ time and displacement can be negative or positive or zero. Therefore velocity can also be negative or positive or zero.
Before we proceed , let's take a coordinate system with origin O. Assume distance on its right side as positive and the distance on its left side as negative.
For e.g., a person is moving with a velocity of 10 m/s due west, (here we are taking west as positive direction) Then it can be said that the person moving with a velocity of +10m/s or simply 10m/s
Now , if another person moves with a velocity of 10m/s due east, ( here we are taking east as negative ) then it can be concluded that the person is moving with a velocity of -10m/s
This all happens(i.e., +10m/s and -10m/s ) just because we have taken the west as positive and the east as negative direction since velocity is changed if the direction is changed