Chapter 6

Question 1

Momentum

Answer 1

• Mass in motion
• Linear Momentum: The product of mass and velocity (p=mv)
• Vector: Magnitude and direction
• SI: kg * m/s
• Change in momentum requires a net force (F=ma)

Question 2

Impulse

Answer 2

• The product of the force and time over which the force acts on an object
• SI: Ns or kgm/s
• Equal to the change of momentum (P=mv-mv0)
  
  • To have same change:
    
    • Small force over long period of time
    • Large force over short time

Question 3

Collision

Answer 3

-Any interaction between objects in which there is an exchange of momentum and/or energy

Question 4

Impulse Momentum Theory

Answer 4

• Stopping times and distances depend on this
• More mass:
  
  • More time and/or force to stop
• Greater change of momentum must occur for mass to stop
• If the same force is applied, more massive object will travel more distance to come to stop

Question 5

Relationship between force and time

Answer 5

• Inversely proportional
  
  • If one is multiplied by 1/2, other is multiplied by 2
• Ex:
  
  • Airbags: extends time required to stop drivers momentum, large force over short time to hit windshield (time increase–> force decrease)

Question 6

Law of Conservation of Momentum

Answer 6

• The moment of all objects interacting with one another remains constant regardless of the nature of the forces between the objects
• If there is no net force, total momentum cannot change
• If internal forces= individual parts of system change, momentum= same
• Momentum= conserved

Question 7

Inelastic Collision

Answer 7

• Where there is a collision between two or more objects and the final kinetic energy is different from the initial kinetic energy
• KE is lost in heat or sound (Not conserved)
• Momentum is conserved

Question 8

Perfectly Inelastic Collision

Answer 8

• Two objects stick together after collision
• Max KE has been lost during collision
• Extreme case of Inelastic collision
• Momentum= conserved

Question 9

Elastic Collision

Answer 9

• Total KE and momentum= conserved
• Objects collide and return to original shape
  
  • Move separately
• Ex: Football player kicks football

Question 10

Center of Mass

Answer 10

-The point at which all of the mass of an object or system may be considered to be concentrated, for the purposes of describing its linear or translational motion only