Physics Chapter 4, 5, 6

Front 1

dynamics is the study of_________, it is about the connection between_____ and ________.

Back 1

why objects move. Force and motion

Front 2

contact forces vs. force of gravity

Back 2

contact = object touching another object

gravity = to touching

Front 3

Is force a vector or scalar?

Back 3

vector

Front 4

Newton's first law of motion:

it is also called:

It does not hold with:

Back 4

an object at rest tends to remain at rest. An object in motion tends to remain in motion

the law of inertia

certain reference frames

Front 5

inertia is:

Back 5

the tendency of an object to retain its state of rest or uniform velocity

Front 6

reference frames where Newton's first law holds are called:

Back 6

inertial reference frames

(does not hold with non inertial reference frames)

Front 7

mass is a measure of:

Back 7

inertia. It will therefore require more force to stop and start objects with more mass (a truck vs. a baseball)

Front 8

mass vs. weight

Back 8

a property of matter vs. a force

Front 9

a net force causes...

Back 9

acceleration

Front 10

Newton's second law:

Back 10

The acceleration of an object is directly proportional to the net force actingon it, and is inversely proportional to the object’s mass. The direction of theacceleration is in the direction of the net force acting on the object.

OR Net force = ma

Front 11

One newton

Back 11

the amount of force required to accelerate a l kg object at 1 m/s^2 --> Thus it equals kg * m/ s^2

Front 12

SI =

cgs =

British =

Back 12

kg, N (kg*m/s^2)

g, dyne (g*cm/s^2

slug, pound (lb)

Front 13

Conversion factors:

1 dyne =

1lb=

slug=

Back 13

=10^-5 N

= 4.45 N

=14.6 kg

Front 14

Start: Chapter 6

work describes:

equation:

vector or scalar?

Back 14

what is accomplished when force acts on an object AND the object moves a distance

W = Fd cos u, F=mag of constant force, d=mag of displacement, u= theta=angle between directions of displacement and force

scalar

Front 15

Work unit:

and it =

Back 15

joules (J)

N*m

Front 16

Work unit cgs, and it equals

Work unit British, and it equals

Back 16

erg, 1 dyne*cm

foot pounds, ft*pounds

1 J=10^7 ergs=.7376 ft*lbs

Front 17

Can a force be exerted on an object and it do no work?

Can there be displacement of an object and no work done on it?

Back 17

Yes - holding up a paper bag - there is no displacement, only force

Yes, walking with a paper bag - there is no force in the direction of displacement on the bag

Front 18

It is important to specify whether you are calculating the work done ON an object of BY an object,

as well as if you are calculating the work done by ONE particular for or the NET forces

Back 18

see other side

Front 19

Can work be negative?

Back 19

Yes, the work of a force can be negative when the object moves in the opposite direction of the force (e.g. friction will have a negative work)

Front 20

to estimate the work done by a varying force, you must graph it and then calculate the area underneath (FII vs. d)

Back 20

see other slide

Front 21

energy is defined as...

Back 21

the ability to do work

Front 22

kinetic energy=

Back 22

the energy of motion

Front 23

translation kinetic energy equation

the work energy principle (words and equation)

Back 23

KE=1/2(m*v^2)

the net work done on an object is equal to the change in an object's kinetic energy

W(net)=change KE= 1/2mv2^2-1/2mv1^2

Front 24

kinetic energy is measured in:

Back 24

joules/ ergs/ foot-pounds, JUST LIKE WORK

Front 25

Potential energy

gravitational potential energy equation:

change in potential gravity =

Back 25

energy associated with forces that depend on the position of an object relative to its surroundings

PEg=mgy, where y=height above a ref level

-Wg (the opposite of work done by gravity)

Front 26

Power

Back 26

the rate at which work is done, or the rate at which energy is transformed.

Front 27

Average power =______or_______

SI units

British and horsepower

Back 27

work/time OR energy transformed/ time

J/s or WATTS

foot-pounds per second, 550 ft-lbs/ sec

Front 28

efficiency equation for power

Back 28

e=P(out)/P(in). Can never be > 1 because energy cannot be created

Front 29

Newton's 3rd law of motion

Back 29

whenever one object exerts a force on a second. The second object will exert an equal and opposite force back on the first

Front 30

uniform circular motion

Back 30

is said to happen when an object moves at a constant speed in a circle

Front 31

radial acceleration = centripital acceleration

Back 31

acceleration that is directed radially and towards the center of the circle, as in uniform circular motion

Front 32

Newton’s law of universal gravitation

equation is called:

Back 32

states that every particle in the universe attracts every other particle with a force proportional to the product of their masses and inversely proportional to the square of the distance between them.

the inverse square law

Front 33

radius of curvature

Back 33

when working with a partial circle, like a curve, this refers to radius.

Front 34

conservative forces vs. non-conservative forces

Back 34

work done depends only on the two positions and not the path taken.

Non-conservative forces depend on the path taken.

Front 35

Law of conservation of energy

Back 35

energy can be transformed into one type or another, but the total energy remains constant

Front 36

when only conservative forces act...

when non-conservative forces act

Back 36

the total mechanical energy is conserved (KE+PE = constant)

Wnc = delta KE + delta PE

Front 37

dissapative forces

Back 37

reduce mechanical energy