Acceleration Acceleration a n Nonuniform motion n n

Acceleration

Acceleration (a) n Non-uniform motion: n n n Different displacements during equal time intervals AND/OR Takes different amounts of time to travel equal displacements. Have a continuously changing velocity.

Change in velocity n When: n Speed of an object changes eg. (0 km/h - 50 km/h) n The direction of motion of an object changes eg. (forward - backwards)

How do you calculate n Remember change in time n Change in velocity equals: Change in velocity = final velocity – initial velocity ?

3 possibilities n Change in velocity is the same sign (+, -) as the initial velocity = speed is increasing.

3 possibilities n n Change in velocity is the same sign (+, -) as the initial velocity = speed is increasing. Change in velocity is the opposite sign (+, -) of the initial velocity = speed is decreasing

3 possibilities speed is increasing. Change in velocity is the same sign (+, -) as the initial velocity speed is decreasing Change in velocity is the opposite sign (+, -) of the initial velocity no change in speed Change in velocity = 0 m/s = (uniform motion)

What is acceleration (a) ? n n Acceleration = the rate of change in velocity (how quickly an object changes in speed and/or direction) Two objects can have the same change in velocity but different accelerations. HOW?

example

Acceleration: n n The direction of acceleration = the direction of CHANGE in velocity Deceleration (slowing down) n Acceleration that is in the opposite direction of motion

4 possible scenarios n 1) speeding up while moving forwards If forward is positive then change in velocity is positive. This means the acceleration is positive. Eg. Go from 0 m/s initial velocity to 10 m/s final velocity n 10 m/s – 0 m/s = +10 m/s

4 possible scenarios n 1) speeding up while moving forwards

4 possible scenarios n 2) slowing down while moving forwards If forward is positive then change in velocity is negative. This means the acceleration is negative. Eg. Go from 10 m/s initial velocity to 4 m/s final velocity n 4 m/s – 10 m/s = -6 m/s

4 possible scenarios n 2) slowing down while moving forwards

4 possible scenarios n n n 3) speeding up while moving backwards Backward direction is given as negative (-). Then the change in velocity is negative Acceleration is negative Eg. Go from -4 m/s initial velocity to -10 m/s final velocity -10 m/s – (-4 m/s) = -6 m/s

4 possible scenarios n 3) speeding up while moving backwards

4 possible scenarios n 4) slowing down while moving backwards Backward direction is given as negative (-). Then the change in velocity is positive n Acceleration is positive Eg. Go from -10 m/s initial velocity to -4 m/s final velocity n -4 m/s – (-10 m/s) = 6 m/s

4 possible scenarios n 4) slowing down while moving backwards