Forces - Physics 11 Flashcards
A force is a ____ or ____.
Push or pull
What are the units of force?
Newtons (N)
What are the four fundamental forces in nature?
Every forces you have “Felt” :
Gravity
Electromagnetic Force
Strong Nuclear Force
Weak Nuclear Force
Newtons First Law:
An object in motion stays in motion,
An object at rest stays at rest,
UNLESS acted on by an unbalenced force
Also called the Law of Interia
What is inertia and its units?
The tendency of matter to keep doing what it is doing (Not to change its motion). Units are kg.
What does Newton’s second law tell us?
How to calculate acceleration. Σ F = ma
N = kg x m/s2
What is Newton’s third law?
For every action (force) there is an equal and opposite reaction (force).
Equal = in magnitude
Opposite = in direction
Gravity is a force that attracts every pair of objects in the universe. The strength depends on their ____ and the ___ ___ ___.
How do you calculate how strong the force is?
Masses and the distance between them.
Fg = M¹M²G
———-
R²
The gravitational field strength is the magnitude of the gravity “force field” created by an object. It depends on how ____ the object is and how ____ ____ it is.
Massive and far away.
What is the formula for the gravitational field strength of an object?
g = G M
———
r²
This is named little g, however it is also called the acceleration due to gravity.
Friction is created when two surfaces . . .
It’s caused by microscopic irregularities . . .
. . . Slide against each other (Kinetic)
or
Try to slide against each other (Static)
kinetic = motion
Static = rest
. . . catches on each other.
When does tension occur? Why does tension occur?
Within a material (usually a rope or string) that is being pulled or streched.
Because every piece of the string pulls on the piece beside it.
- in many situations the rope/string has negliable mass compared to the things its tied to so we assume its massless.
Tension is the same everywhere in a rope and its equal to the force at both ends.
What are the 4 steps to solve tension problems?
1) Draw a FBD for each object
2) Choose an “axis of motion” (can be curved)
3) Find acceleration of the system (use Σ F = ma for ALL objects together)
4) Find tension (use Σ F = ma for ONE object)
Elastic Force (Fe) or Spring Force (Fs). The Force . . .
The force with which a distorted object tries to get it its original/equilibrium state.
Fs = kx
k = spring constant, also known as stiffness (N/m)
x = change in length of the object ( m)
