newton’s laws of motion
TRANSCRIPT
Newton’s Laws of Motion
By Kai Kunitomo
Force
Two types of forces Contact force
Force caused by physical contact Field force
Force caused by gravitational attraction between two objects
Isaac Newton
Born 1642 Went to University of Cambridge in England as
a student and taught there as a professor after Never married Gave his attention mostly to physics and
mathematics, but he also gave his attention to religion and alchemy
Newton was the first to solve three mysteries that intrigued the scientists Laws of Motion Laws of Planetary Orbits Calculus
Three Laws of Motion
Newton’s Laws of Motion are laws discovered by Physicist and mathematician, Isaac Newton, that explains the objects’ motions depending on forces acted on them Newton’s First Law: Law of Inertia Newton’s Second Law: Law of Resultant
Force Newton’s Third Law: Law of Reciprocal
Action
Newton’s First Law
An Object at rest remains at rest, and an object in motion continues in motion with constant velocity (that is, constant speed in a straight line), unless it experiences a net external force.
The tendency to resist change in motion is called inertia People believed that all moving objects
would eventually stop before Newton came up with his laws
Friction
A force that causes resistance to motion Arises from contact between two
surfaces If the force applied is smaller than the
friction, then the object will not move If the object is not moving, then ffriction=Fapplied
The object eventually slips when the applied force is big enough
Friction
Friction was discovered by Galileo Galilee when he rolled a ball down a slope and observed that the ball rolls up the opposite slope to about the same height, and concluded that the difference between the initial height and the final height is caused by friction.
Galileo also noticed that the ball would roll almost forever on a flat surface so that the ball can elevate to the same height as where it started.
Two types of Friction
Static Friction Friction that exists
while the object is stationary
If the applied force on an object becomes greater than the maximum of static friction, then the object starts moving
fstatic≤μstaticn
Kinetic Friction The friction that exists
when an object is in motion
F-fkinetic produces acceleration to the direction the object is moving
If F=fkinetic, then the object moves at constant speed with no acceleration
fkinetic= μkineticn Kinetic friction and the
coefficient of kinetic friction are smaller than static friction and the static coefficient
Newton’s First Law
When there is no force exerted on an object, the motion of the object remains the same like described in the diagram
Because the equation of Force is F=ma, the acceleration is 0m/s². So the equation is 0N=m*0m/s²
Therefore, force is not needed to keep the object in motion, when
The object is in equilibrium when it does not change its state of motion
The car is traveling rightward and crashes into a brick wall. The brick wall acts as an unbalanced force and stops the car.
The truck stops when it crashes into the red car.
But the ladder falls in front of the truck because the ladder was in motion with the truck but there is nothing stopping the ladder when the truck stops.
Newton’s Second Law
The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass
Fnet
Acceleration
Unbalanced Force and Acceleration Force is equal to
acceleration multiplied by mass When an unbalanced
force acts on an object, there is always an acceleration
Acceleration differs depending on the net force
The acceleration is inversely related to the mass of the object
Net Force
Force is a vector Because it is a vector, the net force can be
determined by subtracting the force that resists motion from the force applied to the object.
If the force is applied at an angle, then trigonometry is used to find the force
Fnet
θR
R*cos θR*sin θ
θR
Gravitational Force
The force that exerts all objects toward the earth’s surface is called a gravitational force. The magnitude of the gravitational force is
called weight The acceleration due to gravity is
different in each location, but 9.80m/s² is most commonly used
Calculated with formula w=mg
Newton’s Third Law
If two objects interact, the force exerted on object 1 by object 2 is equal in magnitude but opposite in direction to the force exerted on object 2 by object 1
Forces always come in pair when two objects interact The forces are equal, but opposite in
direction Fg
Fn
As the man jumps off the boat, he exerts the force on the boat and the boat exerts the reaction force on the man.
The man leaps forward onto the pier, while the boat moves away from the pier.
Newton’s Third Law
Force exerted by the wheels
Force exerted by the road
Newton’s Third Law
Newton’s Third Law
Flow backward
Foil deflected down
Foil deflected up
Engine pushed forward
Flow pushed backward
Foil deflected down
Works Cited
Henderson, Tom. Physics. Course home page. 16 May 2008
http://www.glenbrook.k12.il.us/GBSSCI/PHYS/CLASS/newtlaws/newtltoc.html>. Serway, Raymond A., and Jerry S. Faughn. "The Laws of Motion." College
Physics . Fifth ed. 1999.
Benson, Tom. Newton’s Third Law applied to Aerodynamics 21 May 2008 http://www.grc.nasa.gov/WWW/K-12/airplane/newton3.html
Introduction to Rocket Performance. Newton’s Third Law. 12 March 2004 http://www.allstar.fiu.edu/aero/rocket1a.htm
Stern, David P. (16) Newton’s Laws of Physics. 1. Force and Inertia. 9 October 2004 http://www-istp.gsfc.nasa.gov/stargaze/Snewton.htm