1. Answer: System 2
4. Answer: There are exactly 9,000 J of gravitational potential energy in the system because the person is at some position above the ground and the total energy must add up to 18,000 J because energy is always conserved.
only know those 2. yours truly
1)
Study the scenario.
System 1 has a large number of particles, moving slowly on average. System 2 has a smaller number of particles, but they are moving faster on average.
Which system has a higher temperature?
System 2 has a higher temperature because the particles are moving with greater speed. The particles in System 2 have greater kinetic energy than System 1.
System 1 has a higher temperature because there are more particles. A greater number of particles have more kinetic energy than a smaller number of particles.
System 1 has a higher temperature because the particles are moving slowly. The particles in System 1 have greater kinetic energy than System 2.
There is not enough data to tell. The larger number of particles in System 1 may or may not outweigh the increase in movement in System 2.
2)Study the scenario.
A rock falls off the edge of a cliff. The system consists of the rock, the cliff, and the Earth.
Which choice best describes the changes in kinetic and potential energy
Before the rock falls, all the energy is stored as potential energy. The kinetic energy increases as the rock falls because its speed increases. The potential energy decreases as the rock falls because its position relative to the ground decreases. The total energy remains constant.
Before the rock falls, all the energy is stored as potential energy. The kinetic energy increases as the rock falls because its speed increases. The potential energy increases as the rock falls because its position relative to the ground increases. The total energy increases.
Before the rock falls, all the energy is stored as kinetic energy. As the rock falls, the kinetic energy remains constant because the rock’s acceleration remains constant. The potential energy decreases as the rock falls because its position relative to the ground decreases. The total energy decreases.
Before the rock falls, all the energy is stored as potential energy. The potential energy remains the same because the Earth’s pull on the rock does not change. The kinetic energy remains the same because the acceleration remains constant. The total energy remains constant.
3)Which of these correctly describes whether a girl holding a ball in the same position is doing work on the ball?
The girl is doing no work on the ball because she is exerting a net force on the ball.
The girl is doing no work on the ball because the ball is not displaced.
The girl is doing work on the ball because the energy in her muscles changed, even though the ball is not displaced.
The girl is doing work on the ball because the energy of the ball changed, even though it is not displaced.
4)Study the scenario.
A person is standing on a bridge, attached to a bungee cord. The person steps off the bridge and falls down. The isolated system consists of the person, bridge, bungee cord, and the Earth, ignoring friction and air resistance. The amount of energy in the system is 18,000 J when the person is standing on the bridge. At some point during the fall, 6,000 J of energy has been transformed into kinetic energy because the person is moving. Additionally, 3,000 J of energy has been transformed into elastic potential energy because the bungee is stretching. (Air resistance is negligible.)
Which choice best describes the amount and form of the rest of the energy at this point?
There are exactly 9,000 J of thermal energy is the system because the person is heating up as he falls and the total energy must add up to 18,000 J because energy is always conserved.
There are slightly more than 9,000 J of gravitational potential energy in the system because the person is at some position above the ground and the total energy must be slightly more than the initial energy because energy increases as it is transformed.
There are exactly 9,000 J of gravitational potential energy in the system because the person is at some position above the ground and the total energy must add up to 18,000 J because energy is always conserved.
There are slightly less than 9,000 J of gravitational potential energy in the system because the person is at some position above the ground and the total energy must be slightly less than the initial energy because energy is lost as it is transformed.
-Need help with these 4 questions, thanks!
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