Question

Define acceleration and state its si unit.for motion along a straight line ,when do we consider acceleration to be positive and negative? give an exple of a body in uniform acceleration

Answer 1

Velocity describes how position changes; acceleration describes how velocity changes. Two layers of change!
OR
Acceleration of a body is change in speed of a body per time square.
Si units of acceleration - metre/second sq.
When acceleration is in the direction of motion it's positive acceleration and when it acts in opposite directions of motion it's negative acceleration.
Example : A car speeding at a uniform rate