# Newtonian Mechanics

- Created by: LeahhJanee
- Created on: 22-03-17 11:20

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- Newtonian Mechanics
- Newton's First Law
- An object in rest stays in rest and an object in motion stays in motion with the same speed and direction until acted upon by an unbalanced force
- Also known as the Law of Inertia
- If a ball is launched in a vacuum, it will carry on going forever

- Newton's Second Law
- Force is proportional to acceleration (normally) as mass is constant
- If the question is about a rocket and it loses fuel, remember m isn't constant

- F = ma

- Force is proportional to acceleration (normally) as mass is constant
- Newton's Third Law
- For every action, there's an equal and opposite reaction
- Reaction pairs
- Friction and driving force
- Gravity and the reaction force from the ground
- Gravity and air resistance
- Air resistance and driving force

- SUVAT equations
- v = u + at
- v^2 = u^2 + 2as
- s = ut + 1/2at^2
- a = (u+v)t/2

- Scalar and vector quantities
- Scalar = only magnitude
- Speed
- Mass
- Distance

- Vector = magnitude and direction
- Displacement
- Velocity
- Acceleration

- Scalar = only magnitude
- Momentum = mass x velocity
- Conservation of linear momentum = the momentum doesn't change unless an external, unbalanced force is applied
- m1v1 = m2v2

- Moments
- Moment of a force = Fx
- Where x is the perpendicular distance between the line of action of the force and the axis of rotation

- Also known as torque
- Torque of a couple = Fd
- Where d is the perpendicular distance between the two forces
- Couple = two equal forces which act in opposite directions on an object but not through the same point so they produce a turning effect

- Moment of a force = Fx
- Work and energy
- ?W = F?s
- If the force isn't in line with the motion, resolve the vectors

- Kinetic energy = 1/2mv^2
- Principle of conservation of energy = energy cannot be made or destroyed; only transferred
- P = W / t
- Efficiency = useful energy / total energy
- x100 for percentage

- ?W = F?s
- Gravity
- Gravitational field strength = F / m
- Weight = mg
- g = 9.81 ms^-2

- Newton's First Law

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