Acceleration

Definition: Acceleration Vector quantity: magnitude (value) & direction Rate at which an object changes its velocity. “How fast an object is getting faster” If the velocity of an object is changing, it is accelerating!

Definition: Acceleration “How fast an object is getting faster” Every second, object goes 10 m/s faster to the north Units are: Meters per second per second m/s/s

Equation: Acceleration

Animation: Acceleration Physics Classroom: Acceleration Animation

Constant Acceleration Velocity changes by a constant amount each second. The magnitude can change. (How fast it is going) And/or…. The direction can change. An object with a constant velocity is not accelerating.  In this class, ALL acceleration will be constant.

Accelerating Objects Are Changing Their Velocity

Equation: Acceleration 𝑎𝑐𝑐𝑒𝑙𝑒𝑟𝑎𝑡𝑖𝑜𝑛= 𝑐ℎ𝑎𝑛𝑔𝑒 𝑖𝑛 𝑣𝑒𝑙𝑜𝑐𝑖𝑡𝑦 𝑐ℎ𝑎𝑛𝑔𝑒 𝑖𝑛 𝑡𝑖𝑚𝑒 = ∆ 𝑣 ∆ 𝑡 = 𝑣 𝑓𝑖𝑛𝑎𝑙 − 𝑣 𝑖𝑛𝑖𝑡𝑖𝑎𝑙 𝑡 𝑓𝑖𝑛𝑎𝑙 − 𝑡 𝑖𝑛𝑖𝑡𝑖𝑎𝑙 A car goes from 0 m/s to 40 m/s in 10 seconds. What is the acceleration of the car? Accel = 𝑣 𝑓𝑖𝑛𝑎𝑙 − 𝑣 𝑖𝑛𝑖𝑡𝑖𝑎𝑙 𝑡 𝑓𝑖𝑛𝑎𝑙 − 𝑡 𝑖𝑛𝑖𝑡𝑖𝑎𝑙 = 40 𝑚 𝑠𝑒𝑐 − 0 𝑚/𝑠𝑒𝑐 10 𝑠𝑒𝑐 −0 𝑠𝑒𝑐 = 40 𝑚/𝑠𝑒𝑐 10 𝑠𝑒𝑐 = 4 m/s /s

A car traveling at 60 mph accelerates to 90 mph in 3 seconds A car traveling at 60 mph accelerates to 90 mph in 3 seconds. What is the car’s acceleration? Acceleration = Velocity(final) - Velocity(original) time = 90 mph - 60 mph 3 seconds = 30 mph 3 seconds = 10 mph/second

Study in Acceleration Rocket Sled

Graphing: Acceleration Position vs. Time Velocity vs. Time Accel. vs. Time Slope of x vs. t = velocity Slope of v vs. t = acceleration

Graphing: Acceleration

Change in Velocity

- Speed vs Time Graph: Constant acceleration produces a straight line (linear slope, rise/run a = v/t

Free fall The constant acceleration of an object moving only under the force of gravity (g). The acceleration caused by gravity is 10 m/s2 If there was no air, all objects would fall at the same speed Doesn’t depend on mass After 1 second falling at 10 m/s After 2 seconds 20 m/s 3 seconds 30 m/s

Falling Air resistance will increase as it falls faster An upward force on the object Eventually gravity will balance with air resistance Reaches terminal velocity - highest speed reached by a falling object.

Terminal velocity air resistance increases as you speed up Force of gravity is constant air resistance increases as you speed up until the force is equal Equal forces, no acceleration constant velocity terminal velocity

Balloon Racers What will happen if I let go of the blown up balloon? Why did that happen? How can we measure the speed, distance or acceleration of the balloon? A track? Attach the balloon to something?