# Shared Flashcard Set

## Details

Chapter 4 Newtons Laws
questions over chap 4
27
Physics
10/15/2012

Term
 What is a force?
Definition
 interaction between two objects
Term
 What are the four fundamental forces?
Definition
 gravitational, electromagnetic, strong nuclear, weak nuclear
Term
 All common forces are _____.
Definition
 electromagnetic
Term
 The strong nuclear forces holds ____together.
Definition
 the nucleus
Term
 The weak nuclear force is the force that holds ____together.
Definition
 subatomic particles
Term
 The electromagnetic force is the ____.
Definition
 attraction and repulsion between like and unlike objects
Term
 In a free body diagram, if a object is stopped or moving at a constant speed-what does that mean?
Definition
 the forces are balanced
Term
 What is inertia? Who came up with the principle of inertia?
Definition
 property of a mass to resist a change in motion; galileo
Term
 What is newton's first law?
Definition
 the law of inertia; an object at rest will remain at rest and an object in motion will remain in motion at a constant speed in a straight line unless acted on by an outside force
Term
 What does it mean if forces are balanced?
Definition
 the object is either at rest or moving at a constant speed
Term
 HOw do you combine forces to get a net force?
Definition
 if they are on the same line you can add them/subtract
Term
 What is the net force on a 10 N east and 15 N west? is teh object accelearting?
Definition
 5 N west; yes because there is a net force
Term
 When can you use north east and south east?
Definition
 when there is a forty five degree angle
Term
 What is newton's second law? What is the equation that goes along with it?
Definition
 the law of acceleration; acceleration is directly proportional to the net force and inversly proporrtional to the mass. a=F net/m
Term
 you have to do tan^-1 to find theta
Definition
Term
 What is the difference between mass and weight? how do you find the weight if you know the mass? how do you find the mass if you know the weight?
Definition
 mass is a scalar and it is the amount of matter or the amount of inertia; weight is the force of gravity, it is a vector, moves downlards, and is measured in newtons. Fw=mg
Term
 If a mass of 14 kg. is acted on by a force of 28 N. what is the acceleration?
Definition
 28=14g ; g=2 m/s squared
Term
 What determines how much friction is on an object?
Definition
 the normal force-the bigger the normal force, the more friction; and the surface-how smooth is it?
Term
 What is the coefficient of friction? What is the equation for the coefficient of friction?
Definition
 frictioin/normal force = coefficient of friction
Term
 the normal force is equal to the ____when the speed is constant or the object is at rest.
Definition
 weight
Term
 If an object has a mass of 10 kg. and is pulled at a constant speed by a force of 29 N, what is the coefficient of friction?
Definition
 29 N is the friction; coefficient of friction is = 29/9.8 x10
Term
 What two factors affect the air resistance of a falling object?
Definition
 surface area and speed
Term
 What is the terminal velocity?
Definition
 when the weight down equals the air resistance up
Term
 A falling book has a mass of 2.5 kg. The air resistance on the book is 15 N. What is the acceleration of the book?
Definition
 F net=24.5-15=9.5 and a=9.5/2.5=3.8 m/s squared
Term
 What is newton's third law?
Definition
 the law of interaction-for every action there is an equal and opposite reaction; there are two forces and two objects
Term
 What is an action-reaction pair? Why don't they cancel out?
Definition
 equal and opposite forces that are acting on opposite objects; do not cancel because they act on different objects
Term
 in action reaction do both objects move with the same speed? why?
Definition
 no because of the differences in mass
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