Mechanics
Momentum & Impulse
DEF: The product of the mass and velocity of an object
P = mv SI Unit: kg.m/s (vector quantity)
- Assign one direction positive and one negative
Change in momentum
- When an object experiences a net resultant force it will accelerate therefore because v changes so does momentum
- Change in momentum (/\p) = final p - initial p = mv(f)-mv(i)
Momentum is a vector quantity therefore can be represented by an arrow
Newton II in terms of momentum
- When a net force acts on an object the object will accelerate in the direction of that net force
- This means net forces cause a change in velocity and therefore a change in momentum
- Newton's momentum law: the resultant force acting on an object is equal to the rate of change of momentum on the
object
- Fnet= change in P/ change in t
- Fnet = m x change in v/change in T therefore Fnet = ma
Conservation of linear momentum
- Newton's 3rd: during a collision between two objects the two objects will exert forces on each other that are equal in
magnitude but opp in direction
- M(a)Vi(A) + M(b)Vi(b) = M(a)Vf(a) + M(b)Vf(b) (NOT ON DATA SHEET)
- The total momentum of the two objects before the collide is the same as the total momentum after the collide
- STATES: the total linear momentum of an isolated system remains constant
Elastic and inelastic collisions
Elastic: a collision in which kinetic energy is and momentum is constant
Inelastic: A collision in which kinetic is lost and momentum is constant
- When two objects are stuck together it is perfectly inelastic
- Momentum is conserved in both elastic and inelastic
Impulse
DEF: Change in momentum
- The product of the resultant force acting on a body and the time for which it acts
J/change in p = Fnet x T SI unit: N.s = kg.m/s
- A resultant force is needed to bring about a change in momentum of an object
- The longer the force the greater the change in v and thus the greater the change in momentum (impulse)
Momentum & Impulse
DEF: The product of the mass and velocity of an object
P = mv SI Unit: kg.m/s (vector quantity)
- Assign one direction positive and one negative
Change in momentum
- When an object experiences a net resultant force it will accelerate therefore because v changes so does momentum
- Change in momentum (/\p) = final p - initial p = mv(f)-mv(i)
Momentum is a vector quantity therefore can be represented by an arrow
Newton II in terms of momentum
- When a net force acts on an object the object will accelerate in the direction of that net force
- This means net forces cause a change in velocity and therefore a change in momentum
- Newton's momentum law: the resultant force acting on an object is equal to the rate of change of momentum on the
object
- Fnet= change in P/ change in t
- Fnet = m x change in v/change in T therefore Fnet = ma
Conservation of linear momentum
- Newton's 3rd: during a collision between two objects the two objects will exert forces on each other that are equal in
magnitude but opp in direction
- M(a)Vi(A) + M(b)Vi(b) = M(a)Vf(a) + M(b)Vf(b) (NOT ON DATA SHEET)
- The total momentum of the two objects before the collide is the same as the total momentum after the collide
- STATES: the total linear momentum of an isolated system remains constant
Elastic and inelastic collisions
Elastic: a collision in which kinetic energy is and momentum is constant
Inelastic: A collision in which kinetic is lost and momentum is constant
- When two objects are stuck together it is perfectly inelastic
- Momentum is conserved in both elastic and inelastic
Impulse
DEF: Change in momentum
- The product of the resultant force acting on a body and the time for which it acts
J/change in p = Fnet x T SI unit: N.s = kg.m/s
- A resultant force is needed to bring about a change in momentum of an object
- The longer the force the greater the change in v and thus the greater the change in momentum (impulse)
