Physical Science Chapters 13-14

IMA of this pulley

2 (two ropes holding the weight--one pulling up is still holding the weight)

Biblical perspective of conserving energy

We should conserve energy and develop new sources to ensure human flourishing and a thriving creation.

screw

modified inclined plane

geothermal energy

originates from hot water or rock beneath the earth's surface

power formula

power = work/time (J/s=W)

Kinetic energy depends only on____ and ____.

speed and mass

mechanical energy

sum of the potential energy and kinetic energy in a system

Energy

the ability to do work

efficiency

the measure of a machine's ability to convert energy from one form to another

power

the measure of the amount of work done per second

second class lever

the output (resistance) force is between the input (effort) force and the fulcrum

Ideal Mechanical Advantage (IMA)

the ratio of output force to input force (gear system factored by input divided by the output)

biomass energy

uses crop remnants and animal wastes as fuel

hydroelectric energy

uses the gravitational potential energy of water

tidal energy

uses the kinetic energy of the sea as it rises and falls

nuclear energy

uses uranium as a fuel source

Work done on an object

depends on the force parallel to the object's movement

efficiency formula

efficiency= (AMA/IMA)100%

kinetic energy

energy in motion

chemical potential energy

energy that is due to chemical bonds (example baked goods...flour, baking powder, etc taste awful alone, but mixed with a few ingredients and exposed to heat and you get cookies)

Actual Mechanical Advantage (AMA)

equals the ratio of the output force to the input force

mechanical advantage >1

force is multiplied

first class lever example

fulcrum is between the input (effort) and output (resistance) force

fossil fuel

is formed from the remnants of compressed plant and animal matter

mechanical advantage of an inclined plane

length of incline/height of incline (depends on the steepness)

How does a toaster transform energy from one type to another?

It transforms electrical energy into light and heat energy.

pulley system (block and tackle)

A combination of fixed and movable pulleys (everyday use: window blinds)

work

A result of a force moving an object a certain distance.

AMA vs IMA

AMA of a simple machine is always LESS THAN the machine's IMA.

the law of conservation of energy

Energy cannot be created or destroyed; The total energy within a closed system remains constant over time.

Flood model best explains the existence of fossil fuels because

Fossil fuels require large numbers of organisms to be quickly buried. The Flood would have compressed a vast number of organisms underground. We do not see coal or oil being formed today.

Explain the statement "Simple machines make me do more work while at the same time making work easier."

Simple machines make me do more work because all machines have some friction within the machine that uses some of the work that I put in, resulting in less output work than what I actually put in. But simple machines use their mechanical advantage to multiply the effect of my input force, change the output distance, or change the direction of my force. Each of these advantages, even though they take a bit more work, may make work easier to do.

benefit of using hydroelectric dams for energy needs

They are inexpensive to maintain. They produce clean energy. They provide recreational benefits.

benefits of using fossil fuels for energy

They are relatively inexpensive and are still fairly abundant. They tend to be energy dense and are in a form that can be stockpiled without much loss of energy. The technology needed to extract and use them has been around for some time and is well developed.

disadvantage of using hydroelectric dams for energy needs

They take up a lot of space. They are dependent on rain to keep reservoirs full. Reservoirs eventually fill up with silt.

three main forms of fossil fuels

coal, oil, and natural gas

both gravitational potential and kinetic energy examples

a baseball falls in the outfield; a skydiver falls halfway to the earth

gravitational potential energy (examples)

a flowerpot sits on a windowsill

torque

a force that tries to rotate an object around its axis

kinetic energy (examples)

a hammer is used to drive a nail; an automobile travels at 100 m/s

nonrenewable resource

a resource that cannot be replaced such as natural gas

wheel and axle

a type of pulley with a cable in a groove around the perimeter of the wheel

renewable resource

an energy resource that is easily replaced by natural methods

drawbacks of using fossil fuels for energy

burning them contributes to pollution; accidents involving them can have a detrimental impact on the environment; and since they are nonrenewable resources, the supply will eventually run out.