3.5 Newton's Laws of Motion and Momentum Flashcards
What is Newton’s first law?
An object will remain at rest or continue to move with constant velocity unless acted upon by a resultant force.
What is Newton’s second law?
The net (resultant) force acting on the object is directly proportional to the rate of change of its momentum in the same direction.
F = Δp/Δt
What is Newton’s third law?
When two objects interact, they exert equal and opposite forces on each other. (Remember that this must be two separate objects interacting, so the reaction force and weight acting on one block is not a force coupling).
What is linear momentum?
- p=mv
- This is a vector quantity
What is impulse?
- Impulse is the product of force and the time for which this force acts on an object.
- Therefore, Impulse = Δp.
How can you find impulse on a force-time graph?
Impulse is the area underneath the curve on a force-time graph.
What is the principle of conservation of momentum?
- For a system of interacting objects, the total momentum in a specified direction remains constant, as long as no external forces act on the system.
- In a one-dimensional system, total momentum before = total momentum after.
- in a two-dimensional system, total vertical momentum before = total vertical momentum after (+ same in horizontal direction).
- Remember that conservation of momentum applies in a straight one-dimensional line, so you may need to decompose the motion into horizontal and vertical components before applying conservation of momentum.
What is a perfectly elastic collision?
- momentum is conserved
- total energy is conserved
- total kinetic energy is conserved
What is an inelastic collision?
- momentum is conserved
- total energy is conserved
- total kinetic energy is not conserved (e.g. some energy is lost to the surroundings as heat or sound)
