# Science Exam 2

accuracy

how well the measured quantities agree with the true value

precision

how well the measured quantities agree with each other

scientific notation

simplifies the use of very large and very small numbers

conversion factors

equivalent factors that can be turned into each other by dividing one by the other

SI units

physical unit system that is used internationally

length

the measurement of something from end to end (SI Unit is meter)

mass

the quantity of matter which a body contains (SI Unit is kilogram)

volume

the amount of space that a substance or object occupies (SI Unit is L or cm^3)

grams

a metric unit of mass

meters

a metric unit of length

liters

a metric unit of volume

measurement

have two parts: a number and a unit

angular momentum

the product of rotational inertia and rotational velocity

theory of relativity

developed by Einstein when he realized that measurements of time and space are affected by the motion of the observer relative to the object being measured

motion

a change in the location of something relative to something else

reference frame

the perspective from which the motion of something is measured

speed

how fast an object moves

velocity

provides both the speed of an object and the direction of its motion

momentum

depends on the objects mass and velocity, two types linear and angular (p=mv)

law of conservation of momentum

if outside forces are not acting on a system of objects, their total momentum never changes

elastic collisions

collision where the total momentum of two objects before and after the collision must be the same

inelastic collisions

collision where some kinetic energy is transferred into other forms of energy

acceleration

a change in velocity, has a positive direction

deceleration

a change in velocity, has a negative direction

force

a net push or pull that changes the acceleration of an object

net force

the sum of all of the forces acting on the object

balanced force

occurs when the net force is zero, meaning no acceleration

unbalanced force

occurs when the net force is nonzero, meaning acceleration

friction

a contact force

air resistance

friction between the surface of an object and air molecules

gravity

the force of attraction between or among objects having mass

free fall

occurs when gravity is the only force acting on an object

terminal velocity

the maximum speed reached by a falling object

inertia

the reluctance of an object to change its state of motion

Kepler's First Law

each planet moves about the sun in an orbit the shape of an ellipse, while the sun is at one focus

Kepler's Second Law

the straight line joining a planet with the sun sweeps out equal areas in equal amounts of time. A planet travels faster when it is closer to the sun

Kepler's Third Law

the time taken for one orbit is related to the distance from the sun in a specific way and is the same for all planets

Newton's First Law

an object at rest remains at rest and an object in motion maintains its velocity unless it is acted upon by a force

Newton's Second Law

the unbalanced force acting on an object is equal to the object's mass times its acceleration. F=ma

Newton's Third Law

for every action force there is an equal and opposite reaction force

Giga (G)

billion or 10^9

Mega (M)

million or 10^6

Kilo (k)

thousand or 10^3

Deci (d)

one tenth or 10^-1

Centi (c)

one hundredth or 10^-2

Milli (m)

one thousandth or 10^-3

Nano (n)

billionth or 10^-9

kilogram

kg measures mass

liter

L measures volume

centimeter cubed

cm^3 measures volume

meter

m measures length

second

s measures time

gram

g measures mass

milliliter

mL measures volume

centimeter

cm measures length

millimeter

mm measures length

distance

symbol d units are m or km

time

symbol t units are s, hr, min

speed/velocity

symbol v units are m/s or km/hr

momentum

symbol p unit is kg m/s

mass

symbol m units are g or kg

acceleration

symbol is a units are m/s^2

change in velocity

symbol is triangle v unit is m/s

final velocity

symbol Vf unit is m/s

initial velocity

symbol Vi unit is m/s

force

symbol F unit N or kg m/s^2

weight

symbol w unit N or kg m/s^2

Why is it important to have a standard unit of measurement?

To be able to communicate and understand as we discuss science and measurements

You are asked to find the area of a room that is 4.56 m long and 5.668 m wide. How many digits should you show in your answer?

3

What is the value for the acceleration due to gravity on earth?

9.8 m/s^2

What is the difference between speed and velocity?

velocity has direction

What is the difference between mass and weight?

Weight is dependent on where you are, mass is the amount of matter

If you were given that the acceleration of a car had a negative value, what would this mean?

The car is slowing down

If we were to look at your mass on different planets what would we find?

it will not change

If we were to look at your weigh on different planets what would we find

it will change

What happens to the gravitational attraction between objects as the distance between the objects increases?

it decreases

As the mass of an object increases what happens to the gravitational attraction the object feels?

it decreases

Why does a football player at rest tend to remain at rest?

inertia

In a vacuum, which will fall faster: a bowling ball or a marble?

Fall at the same rate, g is the same