# ACCELERATION

#### branchMECHANICS (MOTION)

Coming from SPEED / VELOCITY
=Acceleration= Acceleration is a measure of how quickly an object changes motion (speeds up or slows down). [image:http://i.imgur.com/QIZquLl.png?1] An object will accelerate when there is a net (or unbalanced) force acting upon it. Acceleration is a vector and is in the same direction as the net force. The first car is '''accelerating''' (speeding up) to the right. Its velocity has increased from 30kmh^-1^ to 60kmh^-1^. The second car is '''decelerating''' (slowing down) to the left. Its velocity has decreased from 60kmh^-1^ to 0kmh^-1^. The direction of the acceleration (in this case deceleration) is to the left as a net force in this direction causes the car to slow down. If the direction to the right is labeled as the positive + direction, then left is the negative - direction, then you would write this deceleration with a negative value. E.g. -2.0ms^-2^ ===The cyclist below is accelerating. His velocity is increasing by 1 ms^-1^ each second. Therefore we can say that he is accelerating at a rate of one metre per second per second = 1 ms^-2^.=== [image:http://i.imgur.com/HB2dwMA.png?1] ==Calculating Acceleration== [image:http://zonalandeducation.com/mstm/physics/mechanics/forces/newton/waysToSay/htmlDeltaPDeltaT/deltaPDeltaT_html_m72123c04.gif] The '''average acceleration''' can be calculated by taken the change in velocity divided by the change in time. Note that to calculate the change in velocity you may have to subtract the initial velocity from the final velocity and to calculate the change in time you may have to subtract the initial time from the final time. [image:http://i.imgur.com/XUwb8Zj.png?1] ===The equation for acceleration can also be rearranged to calculate velocity or time:=== [image:http://i.imgur.com/DMVlz21.png]
Credit: Ben Himme, Tristan O'Hanlon