Lecture 2 (Mass, Force, and Newton's Laws) Flashcards
Newton’s First Law
- Law of Inertia
- An object’s state of motion (V) will not change unless a net force acts on the object.
- An object a rest will remain at rest
- An object moving will continue to move with constant V
- no net force=no acceleration
Newton’s Second Law
F=ma
Unit of Force is Newtons (N)
1 N = 1 kg*m/s^2
Newton’s Third Law
For every action, there is an equal but opposite reaction.
If object 1 exerts a force (F1) on object 2, then object 2 exerts a force (F2) on object 1. These forces (F1 and F2), have the same magnitude but act in opposite directions.
form an action-reaction pair. Forces may be equal in magnitude but the effects on the objects may differ.
weight
the gravitational force exerted on an object by the earth
w=mg
where g=gravitational acceleration
units in Newtons
mass
the measure of an object’s inertia, its resistance to acceleration.
intrinsic property of an object, does not change with location
Units in kg
Newton’s Law of Gravitation
Fgrav (w)= G (Mm/r^2)
G=Newton’s gravitational constant (provided)
inverse-square law- the magnitude of the Fgrav is inversely proportional to the square of the distance between the centers of the objects
g=G(M/r^2)
static friction
when there is no relative motion between the surfaces that are in contact
always greater than the kinetic friction
kinetic friction
when the is relative motion between the surfaces (sliding)
Normal Force
N=mg
the perpendicular component of the contact force exerted by a surface on an object.
Force of Kinetic Friction
Ff=(µk)(Fn)
Ff= friction force
Fn= normal force
µk= coefficient of kinetic friction
Maximum Force of Static Friction
Ff max= (µs)(Fn) where, Ff max=maximum static friction force µs= maximum coefficient of static friction Fn= normal force
force due to gravity acting parallel to the inclined plane
=mg sinθ
where θ, is measured between the incline and horizontal
force due to gravity acting perpendicular to inclined plane
mg cosθ
