Module 13 physci

• Aristotle - Believed that heavier objects fall faster
• Terrestrial motion


  Movement of objects on the earth
• Celestial motion


  Movement of objects beyond the earth
• Natural motion


  Motion caused by equilibrium
• Violent motion


  Motion caused by external force
• Voluntary motion


  Willful movement of humans and animals
• Involuntary motion


  "Natural" movement of plants and minerals
• Galileo


  Dropped weights in the Leaning Tower of Pisa to test Aristotle's hypothesis
• Galileo observed that an object and another object twice as heavy will fall at the same time
• Friction


  The opposing motion that makes a moving object stop
• Inertia


  The property of an object to resist change in motion
• Diurnal motion


  The apparent movement of the sky from east to west
• Motion


  The movement of an object from one position to another with time
• When we describe the motion of one object with respect to another, we say that the object is moving relative to the other object
• Although Aristotle and Galileo's ideas were the foundation of today's understanding of motion, their claims were all qualitative
• Physical quantities


  Properties of a material or system that can be quantified by measurement
• Distance


  Total length of the path traveled, following all the turns and/or changes in direction
• Displacement


  Straight line path from the starting point directly to the ending point, including the direction of the travel
• Speed


  Distance covered per unit time
• Units for speed


  • miles per hour (mi/h)
  • meters per second (m/s)
  • kilometers per hour (km/h)
  • centimeters per day
  • light-years per century
• Speed problem


  1. Given: d= 1,000m t= 200 s

  2. Required: Speed

  3. Equation: s=d/t

  4. Solution: s= 1,000m/200s

  5. Answer: The speed is 5 m/s
• Velocity


  The speed and direction of the motion of an object
• Velocity problem


  1. Given: d= 304 m north t= 180 s

  2. Required: Velocity

  3. Equation: v=d/t

  4. Solution: s= 304 m/180s

  5. Answer: The velocity is 1.69 m/s, north
• Acceleration


  When the velocity of an object changes, either due to a change in speed, direction, or both
• Acceleration problem


  1. Given: Vi= 3m/s; Vf= 5 m/s; t= 5s

  2. Required: Acceleration

  3. Equation: a=∆v/t

  4. Solution: a = (5m/s-3m/s) / 5s

  5. a= 2m/s / 5s

  6. Answer: The acceleration is 0.4 m/s2
• Kinematics


  Equations that define the motion of objects without reference to forces
• Linear horizontal motion


  Motion on the x-axis
• Linear vertical motion


  Motion on the y-axis
• Horizontal kinematics problem 1

  1. Given: Vi= 30 km/h; Vf= 60 km/h; Time = 5 mins

  2. Required: a. Distance, b. Acceleration

  3. Equation: a. Distance = , b. Acceleration =

  4. Solution: a. Distance = 360 m, b. Acceleration = 0.0833333 m/s2
• Horizontal kinematics problem 2

  1. Given: a = 26.0 m/s2; Vi= 20 m/s; time = 5.56 s

  2. Required: Distance

  3. Equation: Distance =

  4. Solution: Distance = 360 m
• Horizontal kinematics problem 3

  1. Given: a = 5.50 m/s2; t = 20.25 s

  2. Required: Distance

  3. Equation: Distance =

  4. Solution: Distance = 1127.67 m
• Horizontal kinematics problem 4

  1. Given: Vi= 40 km/h; Vf= 80 km/h; t = 8 hours

  2. Required: Acceleration

  3. Equation: a =

  4. Solution: a = 5 km/h^2

  5. Answer: The acceleration is 5 km/hr^2
• Free-falling motion


  When a falling body/object is free from all restraints - no friction, no air resistance, and only acts under the influence of gravity
• Provided that air resistance is neglected, all objects will fall at an acceleration due to gravity (g) which is equal to 9.8
• Dropped object


  Velocity - increasing, Initial Velocity (Vo) = 0 m/s (initially at rest), Acceleration due to gravity = + 9.8 m/s²
• Thrown upward object


  Velocity - decreasing, Final Velocity (Vf) = 0 m/s (at the highest point), Acceleration due to gravity = - 9.8 m/s²
• Free-falling motion problem 1


  1. Given: Time = 2.78 s, Acceleration = 9.8 m/s2

  2. Required: a. Height (distance), b. Final velocity

  3. Equation: a. Distance =, b. Vf =

  4. Solution: a. Distance = 95.01 m, b. Vf = 0 m/s (object at rest)
• Free-falling motion problem 2


  1. Given: Time = 4 s, Acceleration = 9.8 m/s2

  2. Required: a. Final velocity, b. Height (distance)

  3. Equation: a. Vf =, b. Distance =

  4. Solution: a. Vf = 39.2 m/s, b. Distance = 78.4 m
• Free-falling motion problem 3


  1. Given: Time = 6 s, Acceleration = 9.8 m/s2

  2. Required: Final velocity

  3. Equation: Vf =

  4. Solution: Vf = 58.8 m/s
• Formula card