Chapter 16 Notes
Objectives 1. Describe the effects of gravity, friction, and centripetal force. 2. Explain the difference between weight and mass. 3. Describe Newton’s three laws
Objective 1: Describe the effects of gravity Force applied = the object is pushed or pulled Force that attracts 2 objects together is gravity The 2 things that changes the effects of gravity are:
1) The mass of the objects As the mass increases the gravity increases
2) The distance between the objects As the distance increases the gravity decreases
Objective 1: Describe the effects of friction Friction = force that slows motion or prevents it 3 types: 1. Rolling friction Wheels travel over distance The rougher the surface = greater friction
2.Sliding friction Is increased with an increase in traction
3.Fluid friction Is increased with an increase of surface area of object Includes water and air
The amount of friction can be reduced by using lubricant example: grease and oil
Objective 1: Describe the effects of centripetal force. All moving objects travel in a straight path, unless acted upon by an outside force Centripetal force causes an object to follow a curved path
Example: Turning a corner – car is centripetal force Example: spinning a ball from a string – string is centripetal force
Discovery Video r11883_1000k.wmv r11883_1000k.wmv
Objective 2: Explain the difference between weight and mass. Weight = force of gravity on an object Weight changes, while mass stays constant The pull of gravity is greatest at the poles
Objective 3: Describe how inertia affects an object’s weight Sir Isaac Newton contributions 3 laws of motion: 1. Law of inertia 2. Law of acceleration 3. For every action there is an equal and opposite reaction
Discovery Education Video Basics of Physics: Newton's Laws of Motion
Law of inertia – an object at rest/motion will stay at rest/motion unless acted upon by a force
Example: a person in a car stays in motion after a car wrecks which causes the person to be flown forward, until it is acted upon by another force (airbag)
Inertia is property of matter Increase mass: increase inertia Ex. It takes a stronger force to stop a larger object
2.Law of acceleration Acceleration = force ÷ mass Force = mass X acceleration Mass Force for the same acceleration
3. Newton’s 3 rd law For every action there is an equal and opposite reaction