Physics

• Distance


  How far something has traveled
• Displacement


  The difference between the final position and the initial position, encompasses direction
• Distance vs Displacement


  Distance is a scalar quantity (only magnitude), displacement is a vector quantity (magnitude and direction)
• Displacement example


  • Person travels 8m east, then 3m west. Total distance is 11m, but displacement is 5m east
• Speed


  How fast something is moving (distance per unit time)
• Velocity


  Speed with direction, can be positive or negative
• Speed vs Velocity


  Speed is a scalar quantity, velocity is a vector quantity
• Calculating average speed and velocity

  • Object travels 12m east, then 20m west in 4 seconds. Average speed is 8m/s, average velocity is -2m/s
• Acceleration


  How fast the speed is changing
• Acceleration tells you how fast the speed is changing
• Acceleration of a truck vs sports car


  Sports car has greater acceleration
• Net displacement


  The total distance traveled by an object
• Average velocity


  Net displacement divided by time
• Net displacement is negative


  Average velocity is negative, indicating motion in the westward direction
• Acceleration


  How fast the velocity is changing
• Acceleration examples


  • Truck
  • Sports car
• Acceleration


  • Tells how fast the velocity is changing
  • Defined as change in velocity divided by change in time
• Calculating acceleration


  1. Final velocity - initial velocity

  2. Divided by time
• Acceleration of truck is 2 miles per hour per second
• Acceleration of sports car is 12 miles per hour per second
• Sports car has greater acceleration than truck
• Initial velocity (v0)


  The starting velocity of an object
• Acceleration (a)


  The rate of change of velocity
• Acceleration and velocity have the same sign

  Object is speeding up
• Acceleration and velocity have opposite signs


  Object is slowing down
• Gravitational acceleration (g)


  The acceleration due to gravity, approximately -9.8 m/s^2 on Earth
• Gravitational acceleration acts in the vertical (y) direction, not the horizontal (x) direction
• Calculating vertical velocity over time with gravity


  v_y = v_y0 + a_y*t
• Vertical velocity becomes negative as the object falls downward
• Speed is always positive, while velocity can be positive or negative depending on direction
• Calculating vertical velocity over time for an object thrown upward


  v_y = v_y0 + a_y*t
• Object reaches maximum height when vertical velocity is zero
• After maximum height, vertical velocity becomes negative as the object falls downward
• Vertical velocity changes over time


  1. Positive 19.6 two seconds later

  2. Decrease by 9.8 to positive 9.8 three seconds later

  3. Reach zero at maximum height
• Reaching maximum height


  • Vertical velocity is zero, no longer going up or down
• It took three seconds to reach maximum height
• Position A, B, C


  1. When vertical velocity is zero
  2. At maximum height
  3. After maximum height
• Vertical velocity changes after maximum height


  1. Negative 9.8 four seconds later

  2. Negative 19.6 five seconds later

  3. Negative 29.4 six seconds later
• Once it passes the maximum height, the velocity becomes negative as it is now going in the downward direction
• Projectile


  An object moving under the influence of gravity