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Work
Energy and Power
Kinetic and Potential
Magnets
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100
What are the two parts to scientific work?
Force and Distance
100
What is energy?
The ability to do work.
100
What is potential energy? (3 parts) [can earn partial credit]
The energy an object has because of its position, condition or chemical composition.
100
What are the three properties of magnets? (can earn partial credit)
Magnetic Force, Magnetic Poles, Magnetic Field
100
What is the definition of mechanical energy?
The energy an object has due to its motion and position. ME = KE + PE
200
A boy pulls a wagon 15 m. The force that he applies in the direction of motion is 12 N. How much work does he do?
W = F x d = 12 N x 15 m = 180 joules
200
What is power?
The rate at which work is done.
200
What is kinetic energy?
The energy of motion.
200
What causes an object to be magnetic?
The domains in the object line up and point in the same direction along the magnetic field lines.
200
How does a cow magnet work?
The cow magnet is fed to a cow to attract objects in their digestive system so the objects don't move through their full system.
300
A girl holds a basketball above her head. Is she doing work? Why or why not?
No because the object has to move in addition to having a force acting upon it.
300
Describe the Law of Conservation of Energy.
Energy can neither be created nor destroyed. Only transferred.
300
A rabbit has a mass of 5 kg and is moving at 2 m/s in a grassy field. What is the kinetic energy of the rabbit?
KE = 1/2 x m x v squared = 1/2 x 5 kg x (2 m/s) squared = 10 joules
300
What are at least 3 types of magnets?
Ferromagnets, electromagnets, temporary magnets, permanent magnets, natural magnets...
300
Draw a sketch of the magnetic field around Earth
More lines closer together at poles.
400
Work is only done in the direction of ___________ .
Motion
400
A light bulb uses 300 joules of energy in 6 seconds. What is it's power? (include units)
P = E/t P = 300 j / 6 s P = 50 Watts
400
A bird has a mass of 3 kg and is flying 20 m above the ground. What is the gravitational potential energy of the bird?
GPE = m x g x h = 3 kg x 9.8 m/s squared x 20 m = 588 joules
400
How is Earth like a giant magnet?
It has a magnetic field and magnetic poles.
400
How do you make a temporary magnet?
Rub one pole of a strong magnet in one direction on a magnetic material like a pair of scissors. The domains line up.
500
What is the other way joules is expressed? (The other unit used for work).
Newton-meters.
500
What is the other unit for power besides watts?
Joules / second.
500
In the kinetic energy equation, if the mass of an object increases, what happens to its kinetic energy?
It also increases.
500
How does an aurora form?
The sun ejects charged particles and when they reach Earth, they are guided by its magnetic field. They enter near the poles where the charged particles interact with atoms in the air causing the atoms to emit visible light.
500
What is an example of each of these: Elastic potential energy, Gravitational potential energy, Mechanical potential energy, Chemical potential energy
Elastic potential energy - rubber band, Gravitational potential energy - position, Mechanical potential energy - depends on position, Chemical potential energy - food