SCI MOD 1

• Free-falling objects do not encounter air resistance
• All free-falling objects (on Earth) accelerate downwards at a rate of 9.8 m/s2
• Acceleration due to gravity


  The acceleration for any object moving under the influence of gravity alone, denoted by the symbol g
• The numerical value for the acceleration of gravity is most accurately known as -9.8 m/s2
• Free fall motion


  1. Free-falling objects are acted by gravity (force) alone

  2. According to Newton's Law of Acceleration the object's acceleration follows the direction of the net force, which is downward towards the center of the earth
• Uniformly accelerated motion

  Equations for motion with constant acceleration
• Free fall motion

  Equations for motion with constant acceleration due to gravity (g)
• Free fall is a special case of motion with constant acceleration because acceleration due to gravity is always constant and downward
• The equations for uniformly accelerated motion are applicable to free fall motion except that "a" is replaced by "g"
• Each successive second of the object's fall, the object's speed increases by the same amount: 9.8 m/s
• When an object is thrown up in the air

  The object's velocity decreases as it approaches maximum height, then changes direction and increases as it falls back down
• Acceleration from gravity is always constant and downward, but the direction and magnitude of velocity change
• The mass of the object does not affect its motion when it falls in free fall
• Projectile motion


  The motion of an object thrown or projected into the air with a constant initial velocity that follows a curved path
• Trajectory


  The curved path followed by the projectile
• Range


  The maximum horizontal distance that a projectile covers
• Projectile motion is two-dimensional, consisting of horizontal motion and vertical motion which are independent of each other
• The horizontal motion of the projectile is unaffected by the presence of gravity
• Gravity causes the projectile to accelerate vertically at a constant rate of -9.8 m/s2
• Since there is only a vertical force (gravity) acting upon a projectile, it does not accelerate horizontally
• Equations for Horizontal Motion of a horizontally launched Projectile


  • 𝒗𝒊𝒙 = 𝒗𝒇𝒙
  • 𝒅𝒙 = 𝒗𝒊𝒙t
  • Range = 𝒗𝒊𝒙𝑡
• Equations for Vertical Motion of the Projectile

  • h= 𝒗𝒊𝒚t +

  𝟏

  𝟐 g𝒕𝟐

  • 𝒗𝒇𝒚𝟐= 𝒗𝒊𝒚𝟐 + 2gh
  • 𝒗𝒊𝒚𝟐 = 𝒗𝒇𝒚𝟐 – 2gh
  • 𝒗𝒇𝒚= 𝒗𝒊𝒚 + gt
  • 𝒗𝒊𝒚 = 𝒗𝒇𝒚 - gt
  • h=

  𝒗𝒇𝒚𝟐−𝒗𝒊𝒚𝟐

  𝟐𝒈
• Equations for Horizontal Motion of a horizontally launched Projectile

  1. 𝒗𝒊𝒙 = 𝒗𝒇𝒙

  2. 𝒅𝒙 = 𝒗𝒊𝒙t

  3. Range = 𝒗𝒊𝒙𝑡

  
• Displacement = distance travelled minus initial position
• Distance travelled = area under the curve
• Momentum is a measure of the of an object.

  motion
• Anya knows the velocity of an object. What else does she need to know in order to find the object's momentum?

  its mass
• What is the momentum of a 5 kg object that has a velocity of 1.2 m/s?

  6.0 kg • m/s
• A car has a momentum of 20,000 kg • m/s. What would the car's momentum be if its velocity doubles?

  40,000 kg • m/s
• A bicycle has a momentum of 36 kg • m/s and a velocity of 4 m/s. What is the mass of the bicycle?

  9 kg
• The chart shows masses and velocities of four objects. Which lists the objects in order, from least to greatest momentum?


  Y, W, X, Z

  
• The chart lists the masses of four balls that have the same momentum. Which correctly compares two of the balls?

  The red ball has a greater velocity than the purple ball.

  
• The law of conservation of momentum states that, if left alone, the total momentum of two interacting objects that make up a system .

  remains the same
• Objects 1 and 2 collide and stick together. Which best describes the momentum of the resulting single object?


  It is equal to the momentum of object 1 plus the momentum of object 2.
• Which formula can be used to express the law of conservation of momentum, where p = momentum?

  pi = pf
• The chart show the masses and velocities of two colliding objects that stick together after a collision.

  According to the law of conservation of momentum, the momentum of the object after the collision is ____ kg • m/s.

  1,500

  
• Two carts collide and bounce apart. Cart 1 had a momentum of -6 kg • m/s before the collision. Cart 2 had a momentum of 10 kg • m/s before the collision.

  
  

  What is the total momentum of the carts after the collision?

  4 kg • m/s
• Jerome solves a problem using the law of conservation of momentum. What should Jerome always keep constant for each object after the objects collide and bounce apart?

  mass
• The diagram shows two balls before they collide. What is the momentum of the system after the collision?

  0.2 kg • m/s

  
• According to Newton's third law of motion, which are equal?

  action force and reaction force