Transcript How Do You Describe Force and the Laws of Motion?

How Do You Describe Force and
the Laws of Motion?
Newton’s Laws of Motion
1643 - 1727
They describe the relationship between a
body and the forces acting upon it, and its
motion in response to said forces.
First Law
(Law of Inertia)
An object that is at rest will stay at rest unless
an external force acts upon it.
An object that is in motion will not change its
velocity unless an external force acts upon it.
Second Law
F=m×a
The acceleration of a body is directly
proportional to, and in the same direction
as, the force acting on the body, and
inversely proportional to its mass
a = F/m
A force is any influence that causes an object to undergo a certain
change, either concerning its movement or direction. In other
words, a force can cause an object with mass to change its velocity
(which includes to begin moving from a state of rest), i.e., to
accelerate.
The Unit of Force is the Newton (N)
Definition: The amount of force needed to
accelerate 1 kilogram of mass at the rate of 1
meter per second squared
Newton = kilogram (meter/second)/second
1N = 1kg m/s2
Third Law
When one body exerts a force on a
second body, the second body
simultaneously exerts a force equal in
magnitude and opposite in direction to
that of the first body.
Momentum
Definition: product of the mass and
velocity of an object
p = mv
Units: kilogram meter/second
kg m/s
Newton’s Law of Universal
Gravitation
Every point mass in the universe attracts
every other point mass with a force that is
directly proportional to the product of their
masses and inversely proportional to the
square of the distance between them.
G is the gravitational constant
Calculation of Force Between the
Earth and a 1kg Rock 10meters High
F = Gm1xm2/r2
G = 6.674x10-11Ns2/kg
M1 = 5.972x1024kg
M2 = 1kg
r = 6.341x106m
r2 = 4.059x1013m2
F = 9.8N
a = F/m =9.8N/1kg = 9.8m/s2