Science Midterm

To calculate speed you do distance divided by time.

To get average speed you add total distance and total time and then divide it.

Instantaneous speed:the speed an object is moving at a given in time.

Velocity is determined by two things:the speed of the object and the objects direction.

How to calculate slope =Rise/run

Overview of velocity and acceleration ,the SI unit for speed is m,speed in a given directions is called velocity,slope is found by rise and run.

Object in motion :motion is a position change relative to a reference point.

good reference points:trees,flagpoles,buildings

Relative motion:the people are stationary in motion relative to each other.The people are stationary in motion releative to objects on the ground.

Measuring distance: 1m=100cm,1m=1,000mm,1 km=1,000m

Isaac Newton created newtons first law.

Newtons first law of motion:an object at rest will remain at rest unless acted upon by a nonzero net force and an objject moving at a constant velocity will continue moving at aconstant velocity unless acted upon by a nonzero net force

Inertia:resistance to change in motion

Inertia depends on mass:the greater the mass of an object ,the greater its inertia and the greater the force required to change it’s motion

Newtons secound law of motion:an objects acceleration depends on its mass and on the net force acting on it.

Net force=Mass x Acceleration

Acceleration=net force/mass

F=ma

Newtons third law of motion:If one object exerts a force on

another object, then the second

object exerts a force of equal

strength in the opposite direction

on the first object.

For every action,there is an equal and opposite reaction.

what is matter made of: element:a substance that cannot be broken down into any other substance by chemical orphysical means.

Atoms and Molecules:carbon dioxide made of 1 carbon and 2 oxygen atoms

Water:1 oxygen atom and 2 hydrogen atoms

oxygen:2 oxygen atoms

Ammonia :1 nitrogen atom and 3 hydrogen atoms

Elements vs Molecules: elemenents:cannot be broken down into any other substance,Molecule:group of two or more atoms held by chemical bonds.

Compound: substance of two more elements, chemically combined in a set Chemical formula: uses symbols to show the elements in the compound and the ratio of atoms

Mixture: two or more substances together in the same place, but their atoms are not chemically bonded

Homogeneous mixture: contains very small particles that are not easily recognizable and do not settle out

Heterogeneous mixture: does not appear to be the same throughout and has particles that are large enough to be seen and to settle out

Magnetic attraction:iron objects can be seperated froma mixture using a magnet

Filteration:solids can be seperated from liquids by pouring the mixture through a filter

Evaporation:when left in the open air,liquid solutons can chnage to gas,leaving soid components behind

Distillation:liquids can be seperated from eachother by heating them up to the tempature at which one of the liquids boils.The liquid boils into gas,then gas cools,forming the seperated .

A physical change alters the form or appearance of matter but does not turn any substance in the matter into different A change in matter that produces one or more new substances is a chemical change, or chemical reaction. All chemical changes result in the production of one or more new substances.Matter is neither created nor destroyed in any chemical or physical

change.Energy is the ability to do work or to cause change.Which way is thermal energy flowing in this picture.

Endothermic change: a change in which energy is absorbed

Exothermic change: a change in which energy is released

The energy stored in the chemical bonds between atoms is a form of energy called chemical energy. Does this reaction show a chemical or physical change?

Chemical change 2. Where is chemical energy stored in the methane molecule?

In its chemical bonds 3. Burning methane releases energy. Is this reaction endothermic

or exothermic?

Exothermic

Forms of heat transfer:conduction,convection,radiation

Temperature is a measure of ____________________the average kinetic energy of________

______________the particles in an object_____________________________________.

Two factors that determine an object’s thermal energy are

____________tempature________ and _____________number of particles______________.

Imagine you hold your hand over this pie.

How does your hand feel? Why?