Chapter 3 Accelerated Motion Accelerated Motion

Acceleration  Acceleration = change in speed or velocity over time. It is the rate at which an object’s velocity changes.  It could be speeding up, slowing down, or changing directions

Acceleration  Acceleration = change in speed or velocity over time. It is the rate at which an object’s velocity changes.  It could be speeding up, slowing down, or changing directions Four possibilities  Speeding up forward  Slowing down forward  Speeding up backwards  Slowing down backwards

Acceleration  a = v = v f – v i tt f – t i  Average acceleration = change in velocity during a time interval divided by the time interval

Acceleration  a = v = v f – v i tt f – t i  Average acceleration = change in velocity during a time interval divided by the time interval  Instantaneous acceleration = Drawing a tangent line on the velocity-time graph at the point of interest and calculate the slope

Acceleration  a = v = v f – v i tt f – t i  Velocity with avg. acceleration v = a t v f – v i = a t  v f = V i + a t

Acceleration  a = v = v f – v i tt f – t i  Velocity with avg. acceleration v = a t v f – v i = a t  v f = V i + a t

Acceleration  a = v = v f – v i tt f – t i  Velocity with avg. acceleration v = a t v f – v i = a t  v f = V i + a t

Acceleration

Position with Average Acceleration  An object’s final position is equal to the sum of its initial position, the product of the initial velocity and the final time, and half the product of the acceleration and the square of the final time x f = x i + v i t f + ½ a t f 2

Velocity with constant Acceleration  The square of the final velocity equals the sum of the square of the initial velocity and twice the product of the acceleration and the displacement since the initial time v f 2 = v i 2 + 2a(x f - x i )

Free Fall  Free Fall – The motion of an object when gravity is the only significant force acting on it  Acceleration due to gravity = 9.8 m/s 2 = 32 ft/s 2 = 22 mph/s  Can be + or -

Free Fall  Free Fall – The motion of an object when gravity is the only significant force acting on it  Acceleration due to gravity = 9.8 m/s 2 = 32 ft/s 2 = 22 mph/s  Can be + or -

Free Fall

2 nd Law of Motion  Falling objects – All objects fall at the same rate  Large mass small mass Big Force little acceleration Little force big acceleration

Free Fall rides  Calculating velocity  v f = V i + a t  V i = 0.0 m/s  Acceleration due to gravity = 9.8 m/s 2  Can be + or -

Free Fall rides  v f = V i + a t  V i = 0.0 m/s  Acceleration due to gravity = 9.8 m/s 2  Can be + or -

Free Fall rides  Calculating distance falling x f = x i +v i t f + ½ a t f 2  x i = 0.0 m  V i = 0.0 m/s  Acceleration due to gravity = 9.8 m/s 2  Can be + or -

2 nd Law of Motion  Falling objects – All objects fall at the same rate  Large mass small mass Big Force little acceleration Little force big acceleration

2 nd Law of Motion  Falling objects – All objects fall at the same rate  Large mass small mass Big Force little acceleration Little force big acceleration

Free Fall  Variations:  Acceleration due to gravity = 9.8 m/s 2 on earth’s surface  Depends on mass of object (planet) and distance from center