Physics 11IB – Conservation of Momentum
Learning goal: - Solve problems involving the idea of Momentum and its conservation
Law of Conservation of Momentum
The total momentum of a closed, isolated system of bodies remains constant.
no objects enter nor leave; no external forces
Σpi = Σpf
- Note: When thinking of vertical motion, momentum is not conserved because….
there is the unbalanced force of gravity.
Tennis �and Basketball
The Range
Example 1:
A 0.060kg rifle bullet fires at v = 6.0x102 m/s, the 3kg rifle is being held by a 60kg person. Assuming momentum conserved what is v for the person?
p = p’ 0.06 * 600m/s = (60+3kg) * v v = 0.57m/s
Imagine a model of the second Death Star
(it explodes)
Example 2:
A 3.0kg object initially at rest explodes into three fragments. What is the speed and direction of the 0.80kg fragment
Explosion solution
The three vectors form a right angle triangle
p1 = 1.30kg(15m/s) = 19.5kgm/s S p2 = 0.90kg(20m/s) = 18.0kgm/s W
p3 = √[(19.5)2 + (18.0)2]
= 26.5377kgm/s
p3 = (0.80kg)(v) = 26.5377kgm/s
v = 33.172m/s
tan θ = 19.5/18 = 47.29o
Interactions
Assignment
Tsokos p109�#72-79
July Talk - Guns and Ammunition (2013)