Newtonian physics - key formulas and concepts Flashcards
Newton’s First Law
Objects remain at rest or in uniform motion unless acted upon by an external force (inertia).
A ball rests on the ground until someone kicks it, then flies until some
Objects remain at rest or in uniform motion unless acted upon by an external force (inertia).
Newton’s Second Law
F = ma
F = Force (N)
m = Mass (kg)
a = Acceleration (m/s^2)
A 10 kg object is pushed with an acceleration of 2 m/s^2. The force is F
The force acting on an object is the product of its mass and acceleration. Explains how forces change motion.
Newton’s Third Law
For every action, there is an equal and opposite reaction. Forces always come in pairs.
A ball bounces back after hitting a wall, demonstrating action and react
For every action, there is an equal and opposite reaction. Forces always come in pairs.
Force of Gravity (Weight)
W = mg
W = Weight (N)
m = Mass (kg)
g = Gravitational acceleration (9.8 m/s^2)
A person weighing 60 kg experiences a gravitational force (weight) of W
The weight of an object is the force of gravity acting on its mass. Weight depends on mass and gravity.
Velocity
v = d/t
v = Velocity (m/s)
d = Distance (m)
t = Time (s)
A car travels 100 meters in 5 seconds, so the velocity is v = 100/5 = 20
Velocity is the speed of an object in a specific direction. It measures how far an object travels over a given time in a straight line.
Momentum
p = mv
p = Momentum (kg *m/s),
m = Mass (kg),
v = Velocity (m/s)
A 5 kg ball moving at 10 m/s has momentum p = 5 * 10 = 50 kg * m/s.
Momentum is the product of an object’s mass and velocity. It describes the quantity of motion an object has and how hard it is to stop.
Potential Energy
PE = m g h
PE = Potential Energy (J)
m = Mass (kg)
g = Gravitational acceleration (9.8 m/s^2)
h = Height (m)
A 2 kg object 5 meters above the ground has potential energy PE = 2 kg *
Potential energy is stored energy due to an object’s position in a gravitational field.
Kinetic Energy (KE)
KE = 1/2 m v^2
KE = Kinetic Energy (J)
m = Mass (kg)
v = Velocity (m/s)
A 50 kg runner moving at 4 m/s has kinetic energy KE = ½ × 50 × 4² =
Kinetic energy is the energy of motion. The faster an object moves, the more kinetic energy it has.
Work
W = Fd
W = Work (J)
F = Force (N)
d = Distance (m)
Pushing a box with a force of 10 N for a distance of 3 m does W = 10 √ó
Work is done when a force causes an object to move. The amount of work depends on the force applied and the distance moved.
Power
P = W/t
P = Power (W) [Watt]
W = Work (J)
t = Time (s)
Lifting 50kg of weight up by 2m in 5 seconds uses P = 50 * 2 / 5 = 20 W.
Power measures how quickly work is done or energy is transferred.
Energy Conservation
KE_i + PE_i = KE_f + PE_f
KE = Kinetic Energy (J)
PE = Potential Energy (J)
In a closed system without external forces, the total mechanical energy
In a closed system without external forces, the total mechanical energy is conserved.
