Chapter 3~ Dynamics - Explaining Motion Flashcards
Definitions, key ideas 💡 and formulae
What is Newton’s second law of motion?
The resultant force acting on a body is directly proportional to the rate in change of momentum
The 2 equations for force :
F=ma
F=🔼 p/🔼 t
(p-momentum)
The 2 equations for force :
F=ma
F=🔼 p/🔼 t
(p-momentum)
The mass of an object is 2 things :
- A measure of its inertia
2. It’s ability to resist any change in its motion
If the force is constant, the acceleration is inversely proportional to the…
Mass
So (a is proportional to 1/m)
*inversely means fraction
Define Newton : plus the formula that links
One Newton is the force that will give a 1kg mass an acceleration of 1ms^-2 in the direction of the force.
Formula: 1N =1Kgms^-2
The 6 base units you learn in AS level and their symbols and units :
- Length (x, l, s, etc. ) = metre
- mass (m) = kilogram
- time(t) = second
- electric current (I) =ampere (A)
- thermodynamic temperature (T) = Kelvin
- amount of substance (n) =mol
Definition of a homogeneous equation
When each term in an equation has the same base unit
The 5 multiples, their prefixes and symbols
Kilo (K) 10^3 Mega(M) 10^6 Giga (G) 10^9 Tera (T) 10^12 Peta(P) 10^15
Sub-multiples, prefixes and their symbols
Deci (d) = 10^-1 Centi (c) =10^-2 Milli (m) =10^-3 Micro (u) =10^-6 Nano (n) =10^-9 Pico (p) =10^-12
What is weight?
Weight of an object is a force caused by the Earth’s gravity. It acts vertically down on the object through its centre of gravity
Weight doesn’t affect the rate at which objects falls. Objects that are exactly the same but one is heavier will fall at the same rate. But what does affect the rate then (e.g. Of a feather and a rock)
Air resistance
Definition of inertia :
The reluctance of a body to its change in motion or having its velocity changed
Newton’s first law
An object will remain at rest or in a state of uniform motion unless it is acted on by a resultant force
What is terminal velocity?
It is the maximum velocity of an object when the air resistance is equal to the weight of the object