deck_2384172 (1) Flashcards
Does climbing stairs classify as doing work?
Yes, because you are going against the force of gravity.
Does pushing a shopping cart qualify as doing work? (Assume there is friction.
Yes, you are applying a force against friction.
What is the metric unit for work?
JouleA joule is also a unit for energy
If you exert a force of 10N to lift a box 2m, how much work did you do?
20 J(10N)(2m)=20J
What is the SI unit for power.
Watt
If you exert a force of 5N to travel 10m in 2s how much power was used?
25W(5N)(10m)/2s=25
1492 watts ls about how many horsepower?
2
What can a machine multiply? (Two answers can apply)
Force, Distance
How does a machine make it so that you can apply less force?
The machine allows you to apply the force over a greater distance.Changes the direction of the force.No matter what the total energy required to do the work must remain the same.
Can a machine reach100% efficiency?
No, because some of the work input is always lost to friction.
How do you figure out the ideal mechanical advantage of a pulley system?
Count the number of rope segments that supports the weight.
A machine that is made up of one or more simple machines.
Compound Machine
What is transferred by a force moving an object through a distance?
Energy
The energy of motion.
Kinetic Energy
Ignoring wind resistance and friction, would doubling the height of a roller coaster double its speed? Explain why or why not.
No. The speed would be less than double because V^2=2ad.
What sort of energy would each of the following have?A wound up wind up toy, A stretched rubber band, An inflated tire.
Elastic Potntial
I drop a ball that weighs 2 kg from a 3 m height. What is the balls gravitational potential energy?
About 60 JEP=(2kg)(3m)(9.8m/s^2)
What type of energy increases when an object gets warmer?
Thermal Energy
The energy that is stored in coal is what type of energy?
Chemical
This type of energy is defined as the total potential and kinetic energy of all the microscopic particles in an object.
Thermal Energy
What type of energy supplies your body with energy?
Chemical energy that is stored in the food that you eat.
The Sun uses what sort of energy?
Nuclear EnergySimilar, but opposite to the source of power for nuclear power plants.
What energy conversion happens in the Sun?
Nuclear into LightSolar cell convert light energy into electricity.
Explain what E=mc^2 means in words.
Energy equals mass times the speed of light squared.This shows that energy can be converted into mass and vice versa.
Why are fossil fuels the primary source of energy for the world?
Because they are relatively inexpensive and readily available.Although as easy to reach sources are used up this quality is changing.
How is temperature measured in the metric system?
Celsius Degrees, KelvinCelsius is based on the melting and boiling of water.Kelvin is based on absolute zero.
Thermal energy transfers from one substance to another because of differences in…
Temperature
The measure of the average kinetic energy in an object, is the objects?
Temperature
What three things does an object thermal energy depend on.
Its mass phase and temperature.
What is the difference between conduction, convection and radiation.
Conduction, convection, and radiation are all forms of heat transfer. The differences are in how the heat transfers. Conduction is through direct contact, convection is through fluid movement, and radiation is through electromagnetic waves.
Is metal a good conductor or a bad conductor? Explain why.
Metal is a good conductor because it transfers heat and electricity well.
What is the name of the fluid that is found in air conditioners?
Refrigerant
What heating system involves heating water, and pumping it throughout a house?
Radiant HeatingAs opposed to forced-air that involves a furnace and a blower.
A steam engine is an example of what kind of engine?
External combustion Chemical energy is released outside of the engine which heats water into steam converting heat into work.
What does the first law of thermodynamics state?
That energy cannot be created or destroyed it only changes form.
What does the second law of thermodynamics state?
Thermal energy can flow from colder objects to hotter objects only if work is done on the system.
What does the third law of thermodynamics state?
Absolute zero can never be reached.Absolute zero is where the subatomic particles cannot slow down any more.
What is the SI unit for force?
Newton
What is the total force on a tug of war rope if one team is pulling with 5N of force and the other team is pulling in the opposite direction with 5N of force?
10N of force.
What is the net force on a tug of war rope if one team is pulling with 5N of force and the other team is pulling in the opposite direction with 5N of force?
0N of force.The forces are balanced.
What are two of the major forces that determine the speed of a parachutist?
The downward force of gravity, and the upward force of wind resistance.
What two things make thrown objects follow a curved path.
The initial forward velocity of the abject, and the force of gravity.
Why would a car slide of the road in the wintertime?
If the forward inertia of the car is greater than the friction between the tires and the road, the car will slide of the road.
What does Newton’s second law of motion state?
Force equals mass time acceleration.
What is the difference between weight and mass?
Mass is the measure of the amount of substance in an object. Weight is the measure of the force of gravity on a mass.Weight equals mass times the force of gravity.
What does Newton’s third law of motion state?
For every action there is an equal and opposite reaction.
What is the momentum of a 2kg toy car that is travelling at 3m/s?
6kgm/sm=mv=2kg3m/s.
What can a wave transfer?
Energy
What part of a wave directly relates to the pitch of a sound?
The wavelength or frequency
What happens to the frequency of a wave as the wavelength goes up?
The frequency goes down.
What happens to the volume of a sound as distance increases?
The volume goes down.
How do sound waves spread as they move away from a sound source?
They spread out in all directions.
What part of a wave directly relates to the volume of a sound?
The amplitude
What type of a wave is a sound wave?
Mechanical and compressional
What are the two types of mechanical waves?
Compressional/ longitudinal, Transverse
Name the types of medium can a mechanical wave transfer through?
Solids, liquids, gasses
What can a mechanical wave not pass through?
A vacuum
Explain how refraction works?
When waves travel from one medium to another they change direction.
What can be said about the speed of sound in the air at sea level?
It remains constantAt about 343 m/s depending on the temperature.
What happens to the speed of sound in different types of medium?
It changes
What are four things that can be measured in a wave?
Speed, frequency, wavelength, amplitude
What are two types of waves?
Electromagnetic, mechanical