SCIENCE 9 4TH QUARTER

• Uniform motion


  An object is moving in an equal distance in an equal amount of time, does not speed up nor slows down as time goes by
• Uniformly accelerated motion


  An object maintains a constant change in its velocity in a given time interval

  
• The distance vs time graph of an object moving in uniform motion is a straight line, while an object moving in uniformly accelerated motion has a curved or parabolic graph

  
• Positive acceleration increases velocity and distance covered, while negative acceleration decreases velocity and distance covered

  
• Positive acceleration


  • An airplane preparing for takeoff
• Uniformly Accelerated Motion (UAM)

  The motion of an object where the acceleration is constant

  
• Equations that describe an object in Uniformly Accelerated Motion


  1. vf = vi + at

  2. Δx = (1/2)(vi + vf)t

  
• Free fall


  The motion of an object falling under the influence of gravity, with air resistance negligible

  
• The acceleration due to gravity (g) is -9.8 m/s2
• Projectile motion


  The motion of an object that is thrown and exhibits both horizontal and vertical motion, with the only force acting on it being gravity

  
• The maximum range of a projectile can be attained if the launch angle is 45 degrees

  
• Equations to describe projectile motion

  1. vix = vi cos θ

  2. viy = vi sin θ

  3. Δy = viy t - (1/2)gt2

  4. t = (vfy - viy)/-g

  5. R = 2(vix t)

  
• 1. Greatly affects the trajectory of projectile


  d. launch angle

  
• 2. Vertical velocity of projectile at maximum height


  e. 0 m/s
• 3. Acceleration due to gravity


  b. - 9.8m/s2
• 4. Angle with maximum range

  45
• 5. The sum of two different launch angles having the same range

  90

  
• Uniform motion


  When an object is moving in an equal distance in an equal amount of time, does not speed up nor slows down as time goes by
• Uniformly accelerated motion


  Motion where an object is experiencing a constant acceleration

  
• If an object is experiencing a positive uniform acceleration

  Further increase in velocity and distance covered

  
• Projectile motion


  Motion by which an object is thrown and mainly manifest both horizontal and vertical motion

  
• In freefall, an object can either be

  • thrown upward or downward
• The trajectory and range in the projectile motion is greatly affected by


  • the launched angle and initial velocity

  
• Air resistance affects the horizontal component of the trajectory of a projectile, the effect of it can be minimized by lowering the angle of release

  
• In the javelin, to gain more distance, athletes will hold the javelin up higher to create a greater height of release
• As the height of release decreases, the angle of release decreases also
• Momentum (p) of an object is the product of its mass and velocity
• Impulse (I) is the product of the force and the time over which the force is applied
• Momentum and Impulse are equal in magnitude when there is no energy loss
• Real-life examples where momentum and impulse are observed

  • Volleyball spike
  • Pulling paper under a coin
  • Balloon prick with a needle
  • Collision of billiard balls
  • Gun and bullet fired
  • Football player pinned down
  • Truck vs car momentum
  • Truck at different velocities
• To minimize the effect of the force on an object involved in a collision

  Increase the time of impact
• To maximize the effect of the force on an object involved in a collision

  Decrease the time of impact
• The total momentum of a system does not change if no net external forces are acting
• Elastic Collision


  • After two objects collide, they move separately with no change in kinetic energy. The total momentum and the total kinetic energy remain constant throughout the collision.

  
• Inelastic Collision


  • The final kinetic energy of the system is less than the initial kinetic energy
• Perfectly Inelastic Collision


  • Objects collide and move together as one mass after the collision
• In a perfectly inelastic collision, the total kinetic energy is not conserved because some objects can be deformed and lose their original shapes when they stick together
• Conservation of momentum explains why a gun or cannon recoils backward when it is fired
• Potential energy


  The energy of the object based on its structure and position
• Kinetic energy


  The energy of the moving object