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February 2014. ACCELERATION. How do we measure changes in velocity?. Acceleration The rate at which velocity changes An object accelerates if its speed, direction or both change. The acceleration of an object is directly proportional to the net force applied to it
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February 2014 ACCELERATION
How do we measure changes in velocity? • Acceleration • The rate at which velocity changes • An object accelerates if its speed, direction or both change
The acceleration of an object is directly proportional to the net force applied to it • The BIGGER the force, the MORE the acceleration • The acceleration of an object is inversely proportional to the mass of the object • The BIGGER the mass, the LESS the acceleration
Calculating average acceleration • Acceleration = ∆V/ t Vf = final velocity Vi = initial velocity
Units for acceleration: • Speed and velocity are easily measured in distance/time units (such as km/hr, m/s) • Units for acceleration are more complicated: • Sample problem: What is the acceleration if we speed up from 10km/h to 30 km/h in 10 seconds? • Acceleration= ∆V = 30 km/h – 10 km/h = 2 km/h/s t 10 sec • Distance/time/time
Summary • How fast = SPEED • How fast and in what direction = VELOCITY • How quickly velocity changes = ACCELERATION • The term “acceleration” - velocity increases • The term “deceleration” - velocity decreases (or negative acceleration)