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Chapter 4 Newtons Laws
questions over chap 4
27
Physics
12th Grade
10/15/2012

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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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