Question

define accetrtion and state is SI unit for motion along a straight line when do we consider the accetrtion to be (1) positive (2) negative give examples​

Answer 1

Answer:

Rate of change in Velocity or speed is called acceleration.

SI unit :-

$m\div s {}^{2}$

we say positive acc when the speed of an object is increasing.

example1:- when a car driver presses accelerator the speed is said to be increasing at a rate say +1m/s^2 so we can understand the speed of the car is increasing at a rate of 1m/s per second

when the speed is decreasing, we say negative acceleration.

example2:- when a car driver presses brakes, the car speed decreases at a rate say -5m/s^2 . this means the car's speed in decreasing at a rate of 5m/s per second