64 terms

Work

Transfer of energy as the result of motion

Explain force and distance in work

Both have to be in the same direction

Equation for work

Force times distance

Units for work

N x m. Kg x m/s^2 x m. Kg x m^2/s^2. Joule

Work equation examples

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Power

How fast the work is done

Equation for power

Work/time

Units for power

J/s. Kg x m^2/s^2/s. Kg x m^2/s^3. Watt

American units for power

Ft lb/s. Horsepower

Conversion from ft-lb/s to watts to horsepower (hp)

550 ft lb/s = 746 w = 1 horsepower

Power equation examples

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Energy

Ability to do work. Ability to cause a change in itself or its environment

Five main types of energy

Mechanical. Thermal. Electromagnetic. Chemical. Nuclear

Mechanical energy

moving objects

Thermal energy

Heat, Temp, etc.

Electromagnetic energy

Light. X Rays. Radio waves.

Chemical energy

Endothermic and exothermic reactions

Nuclear energy

radio activity, nuclear fusion, nuclear fission

What can the types of energy be divided into

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Kinetic energy

Energy due to the motion of an object

Equation for kinetic energy

KE=1/2mv^2

Units for kinetic energy

Kg x m^2/s^2 or joule

What happens to the kinetic energy of you double the mass

Ke is doubled

What happens to the kinetic energy if you double the velocity

Four times the ke

Potential energy

Energy due to the position or condition of an object

Gravitational potential enegy

Due to position

Calculation for gravitational potential enrgy

Pe=Weight x height. Pe=mass x g x height

Example of condition of potential energy

Rubber bands. Springs

Examples for equation of potential energy

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Law of conservation of energy

Energy cannot be created or destroyed. Can change forms. Total energy in the universe is constant

Describe energy of rock on top of hill

Top no ke all pe. Middle pe decreases because height decreases. Ke increases because speed increases. Bottom all ke

What would happen to a pendulum if there was no friction

It would go forever but in real life friction changed mechanical to thermal

Thermal energy

Total energy of the particles that make up a substance

What happens to the thermal energy when the mass is greater

More energy

Is the thermal energy related to the motion f the ovject

No

Temperature

Average kinetic energy of the particles in a substance

Does the number of particles affect the temperature

No

Explain thermometer

Liquid expands when heated. Length of column indicates temperature

Celsius to farenheit

Tf=9/5tc+32

Fahrenheit to Celsius

Tc=5/9(tf-32)

Kelvins to celsius

Tc=tk-273

Celsius to kelvins

Tk=tc+273

Si unit for temperature

Kelvin. No negative temperatures

Temperature conversion examples

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Heat

The transfer of energy from an object at a higher temperature to one at a lower temperature

Compare work and heat

Both a transfer of energy. Both measured in joules. Both not a property of a substance

Difference between work and heat

Work is energy transferred by mechanical means. Heat is energy transferred by thermal means

Si unit for heat and thermal energy.

Joule

Calorie

Amount of heat required to raise the temperature of one gram of water by one Celsius degree

calorie to kilocalorie to Calorie

1 kcal=1000 cal=1 Cal

calorie to joule

1 cal=4.19 J

BTU

British thermal unit. Amount of heat required to raise the temperature of one pound of water by one Fahrenheit degree

BTU to calorie

1 BTU=252 cal

List units for heat and thermal enetgy

Joule. calorie. Kilocalorie. Calorie. BTU

Specific heat (c)

Amount of energy needed to increase the temperature of one kilogram of s substance by one Celsius degree. Unique for every substance

Specific heat for water

4186 j/kg•C

How do you measure thermal energy

You cant. Can only calculate change in thermal energy

What is the change in thermal energy

Energy lost or gained

Equation for change in thermal energy

Q=mass x specific heat x change in temp

Units for change in thermal energy or q

Kg•j/kg•c • c=j

Examples for q equation

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Calorimeter

Instrument used to measure changes in thermal energy because it is designed so energy cannot escape or enter the system

Method of mixtures

When substances of different temperatures are combined They end up at the same temperature. Equilibrium

What is the perfect situation of method of mixtures

Amount of thermal energy lost(q)=amount of thermal energy gained(q)