Dynamics Flashcards
Newton’s 1st Law
Every object continues in a state of rest or in uniform motion unless a net force acts upon it
Net force = 0 e.g. Normal - Gravity = 0 & Friction - Applied force = 0
Newton’s 2nd Law
The change in momentum per second is proportional to the applies force F=ma
Newton’s 3rd Law
To every action there is an equal but opposite reaction
What is mass?
Measure of inertia, reluctance of an object to move under a force (kg) - constant for object
What is momentum?
momentum = mass(kg) x velocity (ms-1) kg/m/s
What is weight?
Gravitational force with which an object pulls a mass towards its centre - not constant
weight(N) = mass(kg)g(9.8ms^-1)
What are the 4 fundamental forces?
- Gravitational force always attractive - between all masses
- Electromagnetic forces - electrostatic & magnetic
- Strong force - nuclei of atom
- Weak force - certain nuclear processes
Name some mechanical forces
normal force, friction, tension, centripetal force
What is normal force?
upward force exerted by a supportive surface on an object - always perpendicular to surface - equal but opposite to weight & any other forces applied downwards
What is friction?
Opposes motion of object trying to move an item in or on a medium
When does the friction force = the force applies?
When the force is applied is less than the maximum stationary friction
Calculation for friction
friction = μN
μ is either the static or kinetic friction coefficient
N is the normal force
Calculate the normal force?
*only gravity N=mg
*force applied downwards N=mg + F
*Tension pulls mass up N=mg - T
How to calculate force with friction?
(F-μN) = ma
What is tension?
Force acting on an object via rope/string
T = mg + ma
