4. Momentum and Energy Flashcards
(6 cards)
1
Q
What is Momentum
A
- Momentum is a property of moving objects
- It is the product of an objects mass and velocity
- It is conserved in a closed system unless an external force acts
- A vector quantity, that can be transferred between objects via a force over time
- Units: kg m/s
2
Q
Formula for Momentum
A
p = mv
∑ MVi = ∑ MVf
Δp = MVf - MVi = FΔT
3
Q
What is the Conservation of Momentum
A
- In an isolated system, the total momentum before and after a collision remains constant
- This is a fundamental law of physics (no known violations)
Formula:
- ∑ MVi = ∑MVf
or
- m1vi1 + m2vi2 = m1vf1 + m2vf2
4
Q
Internal vs. External Forces
A
- Internal Force: The force within the system (e.g. particles in a baseball)
- External Force: Force between system and outside object (e.g. bat hitting ball)
Key Principle: If an internal force gives momentum to one part, another part must gain the same momentum in the opposite direction
Example: Rocket Propulsion - gas goes backwards, rocket moves forward (Newton’s 3rd Law)
5
Q
What is Impulse
A
- Impulse is the effect of a force applied over time; it causes a change in momentum
- It is calculated from Newton’s second law, and rearranged to:
Δp = MVf - MVi = FΔT
- Units: N or KG M/s
6
Q
Impulse Graph Interpretation
A
- Area under Force vs. Time curve represents impulse
- Wider Base (longer time) = lower peak force, same for impulse
