Final Flashcards
Does pushing a shopping cart qualify as doing work? (Assume there is friction.
Yes, you are applying a force against friction.
Does climbing stairs classify as doing work?
Yes, because you are going against the force of gravity.
What is the metric unit for work?
Joule
A 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
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.
How do you figure out the ideal mechanical advantage of a pulley system?
Count the number of rope segments that supports the weight.
What is a machine that is made up of one or more simple machines called?
Compound Machine
What is the energy of motion called?
Kinetic Energy
I drop a ball that weighs 2 kg from a 3 m height. What is the balls gravitational potential energy?
About 60 J
EP=(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 Energy
Similar, but opposite to the source of power for nuclear power plants.
What energy conversion happens in the Sun?
Nuclear into Light
Solar cell convert light energy into electricity.
How is temperature measured in the metric system?
Celsius Degrees, Kelvin
Celsius 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 affect an objects thermal energy?
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 Heating
As 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. (Projectile Motion)
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/s
m=mv=2kg3m/s.
What can a wave transfer?
Energy
Mechanical Waves only transfer energy, and not particles.
Explain how you would measure frequency?
Pick a particular time period and count how many waves pass by over a certain time.
How would you measure amplitude?
Determine the distance between the rest position to either a crest or a trough.
What happens when a wave “bounces” off of a solid object?
Reflection
What happens when a wave changes direction because it has went from one medium to another?
Refraction
What happens when a wave passes through multiple openings and interferes with itself?
Diffraction
What happens when two waves occupy the same space?
The waves could build on each other (constructive interference) if the peaks and troughs line up.The waves could have destructive interference if the peaks and troughs are opposite of each other. Or anything in-between.
Describe the Doppler effect.
Objects moving toward you will make sounds in a higher pitch. Objects moving away will have a lower pitch.