Linear Momentum

Question 1

Linear Momentum

Answer 1

The product of mass and velocity

• p= mv
• Symbolized by p
• Momentum is measured in units of kg m/s and is a vector (magnitude and direction)
• The more momentum an object has the more impact it has

Question 2

Newton’s Second Law in Terms of Momementum

Answer 2

F= Δp/Δt is the same as F= ma

Δp/Δt= Δ(mv)/Δt = m(Δv/Δt)= ma

Question 3

Impulse

Answer 3

The product of force and the time during which it acts

• Vector quantity symbolized by J
• J= FΔt

Question 4

Impulse-Momentum Theorem

Answer 4

J= Δp

Another way of writing Newton’s second law

• Impulse delivered to an object is equal to the resulting change in its linear momentum

Question 5

Impulsive Forces

Answer 5

Forces that exist over a short period of time

• A large change in momentum divided by a short time interval makes for painful impact
• E.G. concrete is hard and has no cushion, making its impact time of any object hitting concrete short

Question 6

Conservation of Linear Momentum

Answer 6

States that in an isolated system, the total linear momentum will remain constant

• Two interacting objects exeperience equal but opposite momentum changes (assuming there are no external forces), which implies that the total linear momentum of the system will remain constant
  
  • Any number of interacting objects, each pair that comes in contact will undergo equal but opposite momentum changes, so the result described for two interacting objects will hold true for any number of objects, gievn that the only forces they feel are from each other

Question 7

Internal Forces

Answer 7

Forces that occur within the system

Question 8

Collisions

Answer 8

Conservation of linear momentum is used to analyze collisions

• Objects involved in a collision exert forces on each other during the impact, these forces are internal(within the system) and the system’s total linear momentum is conserved
• Collisions are classified into two major categories:
  
  • Elastic
  • Inelastic
• In all isolated collisions, elastic and inelastic, conservation of linear momentum states that
  
  • total p_{before collision}= total p_{after collision}

Question 9

Elastic Collision

Answer 9

A collision is said to be elastic if kinetic energy is conserved

• In an isolated system, momentum and kinetic energy are conserved
• Ordinary collisions are never truly elastic because there is always a change in energy due to energy transferred as heat, deformation of the objects, or the sound of the impact
  
  • If objects do not deform on collision, the loss of initial kinetic energy is small enough to be ignored and can be treated virtually elastic

Question 10

Inelastic Collision

Answer 10

Collisions in which the total kinetic energy is different after the collision

• Momentum is conserved and kinetic energy is not conserved
• Perfectly or totally inelastic collision: momentum is conserved, kinetic energy is not conserved and the objects stick together
  
  • m_redv_red + m_greenv_green= (m_red + m_green)v’