Chapter 13 Newton s Laws Sir Isaac Newton formulated four three accepted laws pertaining to the relationship of force and motion First law no force law If an object is at rest it will stay at rest If an object is in motion it will stay in motion in a straight line at a constant speed o Objects will come to a rest due to friction however this law is applied when there is no friction Second law net force the amount of force remaining after one subtracts forces in the opposite present direction will cause an object to accelerate o Has two corollaries The greater the force on an object the greater the acceleration The greater the mass the smaller the acceleration This is because there is a greater pull of gravity on the more massive object o Gravity causes all objects to accelerate at the same rate o Can be put in mathematical form a F m or F ma F is the net force a is the acceleration and m is the mass Pound the net force of the mass of a slug made to accelerate 1 ft sec2 Newton the net force of the mass of a kilogram made to accelerate 1 m sec2 Dyne the net force of the mass of a gram to accelerate 1 cm sec2 Third law For every action there is an equal and opposite reaction o One cannot exert force on an object without the object exerting force back Fourth law The attraction force between two masses can be determined by multiplying the amount of mass in one object by the amount of mass in the second object Then diving this product by the square root of the distance between the centers of the two objects Chapter 14 Math Examples of Newton s Second Law Question In 7 seconds how far will a wagon move on a frictionless level surface if a girl pushes on it with a force of 20 pounds The mass of the wagon is 5 slug equal to 16 pounds on Earth Keep in mind that 1 pound slug feet sec2 First we must find the acceleration with the equation a F M a 20 slug feet sec2 5 slug which is 40 feet sec2 After the distance is acceleration is found we can find the distance moved with the formula used on the o A F 20 slug feet sec2 M 5 slug last exam D 1 2a t2 o A 40 ft sec2 T2 49 seconds D 1 2 40t sec2 49 seconds2 which equals to 980 feet This is your FINAL answer for the question Some problems may require a multi step process Newton says that in order for an object to accelerate there must be net force acting on it There are three ways to accelerate Chapter 15 Circular Motion Go faster Go slower Go around a curve changing direction When going around a curve an inward force is applied This is called centripetal force the real force that pushed inward on a curve A centripetal force can come from the force of gravity an electromagnetic force the strong interacting force or weak interacting force According to Newton s third law for every action there is an equal and opposite reaction there has to be an opposite reaction acting on centripetal force This is called centrifugal force the false force that pushes outward in a curve This is force that is felt when the vehicle moves around a curve The orbital velocity of Earth is 18 000 miles per hour This is the speed at which objects such as satellites orbit the Earth Angular momentum the tendency for an object to continue in a circular motion Chapter 16 Work and Energy Energy is defined as the ability to do work In order for one to perform work three requirements must be met A force must be applied to an object The object must move through a distance The direction of the force and the direction of the displacement must be in the same dimension The units by which work and energy is measures involve a unit of force and a unit of distance Example if an object is pushed one foot with a force of one pound then one foot pound of work is done Joule a newton meter o A newton is about 1 5 of a pound Erg a dyne centime Power is the work done divided by the amount of time required to do the work Watt A joule of work done in one second Horsepower 746 joules of work done in one second Chapter 17 Kinetic and Potential Energy Kinetic energy is energy found in all moving objects This creates the ability to do work The amount of kinetic energy found in an object is done by taking of its mass and multiplying it by the velocity squared o If a car is travelling at 60 mph the damage will be 4x as bad than travelling at 30 mph Example if the mass is 2 5 2 3600 3600 5 2 900 900 o 3600 900 4x as bad There are several types of potential energy Due to position o The location of an object can give it the ability to do work Example The rock on top of a cliff has potential to do work by falling In a stretched compressed string Charged particles o When the coils are displaced they ll try to return to their original potions o Moving charged particles can exert a force and move an object some distance Electricity is nothing more than a stream of moving electrons Chemical potential energy o Released during a chemical reaction Nuclear potential energy o Released from the nucleus of an atom Stars shine due to nuclear energy Chapter 18 Conservation of Energy The conservation of energy law states that energy cannot be created or destroyed only transferred One cannot create or destroy energy also known as the first law of thermodynamics A rock sits on top of the cliff The rock has potential energy As the rock falls down the cliff its potential energy decreases Even though the potential energy is gone it gains kinetic energy The faster atoms more more heat is produced Random kinetic energy is heat Chapter 19 Heat and Temperature Heat and temperature is not the same thing Heat the total random kinetic energy found in all atoms in an object Temperature a function of kinetic energy of each atom o If an atom oscillates violently its temperature is high If it oscillates slowly its temperature is lower Things expand when heated and a thermometer can measure this increase and decrease in temperature There are two types of standard thermometers that measure the expansion and contraction of atoms Celsius 0 is the freezing point of water and 100 is the boiling point of water Fahrenheit 32 is the freezing point of water and 212 is the boiling point of water How to convert from Celsius to Fahrenheit F 9 5C 32 How to convert from Fahrenheit to Celsius C 5 9 F 32 There is a type of thermometer called a …