Mechanics 5 - Momentum Flashcards
1
Q
p formula
A
p = mv
2
Q
Different formula with F (when mass not constant)
A
Related to second law:
F=ma
F = ∆(mv)/∆t
F = ∆p/∆t
3
Q
Definition of p
A
Rate of change of p is proportional to net external force
4
Q
Impulse momentum theorem
A
F∆t = ∆p
5
Q
Law of conservation of momentum
A
∆p = 0 as long as there are no external net forces, just the forces between the colliding object (Newton’ s 3rd law)
6
Q
Two types of collisions
A
Elastic and Inelastic
7
Q
Inelastic
A
p is conserved but KE is not (some is converted to other forms of energy)
8
Q
Elastic
A
p is conserved and KE is as well
9
Q
How to solve collsion problems
A
- Choose a boundary to define the system of interest
- what is colliding + their forces
- If only one object, all forces are external
- If its two objects + elastic then no elastic forces
-Which forces are internal+external
- Make complicated forces between objects internal forces - Draw the system before + after collision
- Find co-ordinate origin and determine which d is +ve and if more than one direction, divide into vector components
- Is it elastic/inelastic
10
Q
Properties of a totally inelastic collision
A
*The objects stick to each other
*Linear p of the SYSTEM is conserved
*But KE of the SYSTEM is not
11
Q
Properties of a elastic collision
A
