energy
Here are flashcard questions based on the content of the provided "Energy Review Packet"1:
Work
Q: What is work in terms of energy?
A: Work is a form of energy.
Q: What is the standard metric unit of work?
A: The Joule (Newton- meter).
Q: Is a Watt the standard metric unit of work?
A: No, a Watt is the unit of power, not work.
Q: What units are equivalent to a Joule (unit of work)?
A: Newton times meter (N- m) and kg- m²/s².
Q: Is work a time-based quantity?
A: No, work itself is not time-based; power is.
Q: Does applying a force to prevent movement (like Superman holding a truck still) count as work done?
A: No, if the object does not move, no work is done.
Q: Does carrying a bucket horizontally at constant height involve work done by the upward force?
A: No, because the force is perpendicular to the displacement.
Q: If a force acts at 90 degrees to the direction of motion, what work does it do?
A: No work is done.
Q: If a force acts opposite to the direction of motion, what kind of work is done?
A: Negative work.
Q: If a force is the only one doing work on an object, what happens to the object's mechanical energy?
A: The object will gain or lose mechanical energy.
Power
Q: What does power measure in physics?
A: How fast work is done.
Q: What is the standard metric unit of power?
A: The Watt.
Q: If two people do the same job but one does it faster, who has more power?
A: The person who does it faster.
Q: Is Newton- meter a unit of power?
A: No, it is a unit of work.
Q: How is power calculated when a force moves an object at constant speed?
A: Power = Force × Speed.
Kinetic Energy
Q: What does kinetic energy depend on?
A: Mass and speed of the object.
Q: Does an object at rest have kinetic energy?
A: No.
Q: Can kinetic energy be negative?
A: No.
Q: If an object's mass doubles, what happens to its kinetic energy (if speed is constant)?
A: It doubles.
Q: If an object's speed doubles, what happens to its kinetic energy?
A: It quadruples.
Q: If work is done on an object by an outside force, what happens to its kinetic energy?
A: It will gain or lose kinetic energy.
Potential Energy
Q: What is potential energy?
A: Energy stored in an object due to its position.
Q: What does gravitational potential energy depend on?
A: Mass, height, and gravity.
Q: If the mass of an elevated object is doubled, what happens to its gravitational potential energy?
A: It doubles.
Q: What is the unit of potential energy?
A: The Joule.
Q: Is potential energy lost as an object free-falls?
A: Yes.
Mechanical Energy
Q: What is the total mechanical energy of an object?
A: The sum of its potential and kinetic energy.
Q: Is mechanical energy always conserved?
A: No, not when non-conservative forces (like friction) do work.
Q: What happens to mechanical energy when friction does work?
A: The total mechanical energy changes.
Application & Problem Solving
Q: If two cars of different masses are lifted to the same height, how does the work required compare?
A: Lifting the more massive car requires more work.
Q: If 50 J of elastic potential energy is stored in a bow, how much kinetic energy will the arrow have when released (ignoring losses)?
A: 50 Joules.
Q: How much net work is done on a box while carrying it at constant speed across the floor?
A: Zero Joules.
Q: If the speed of a skidding car triples, by what factor does the stopping distance increase (assuming same braking force)?
A: The stopping distance increases by a factor of nine.
Q: What is the kinetic energy of a 10-Newton object moving at 1 m/s?
A: Cannot be determined without knowing the mass.
Q: Can a stationary object have energy?
A: Yes.
Q: What is the power required to do 1000 J of work in 20 seconds?
A: 50 Watts.
Calculations & Scenarios
Q: How do you calculate the work required to lift a 2.5-kg object to a height of 6.0 meters?
A: Work = mass × gravity × height.
Q: How do you calculate the power rating of a person climbing stairs?
A: Power = (mass × gravity × height) / time.
Q: What is the work-energy theorem?
A: The change in kinetic energy equals the net work done on an object.
Q: What happens to kinetic and potential energy as a roller coaster moves along a track (neglecting friction)?
A: The total mechanical energy remains constant, but kinetic and potential energy convert into each other.
Work-Energy Bar Charts & Equations
Q: What terms are canceled in the work-energy equation for a ball falling from rest with no air resistance?
A: Initial kinetic energy is zero; work by non-conservative forces is zero.
Q: What does the work-energy equation simplify to for a frictionless inclined plane?
A: KEi + PEi = KEf + PEf.
Force and Energy in Collisions
Q: How is the force calculated when catching a baseball over a certain distance?
A: By using the work-energy principle: work done by the force equals the change in kinetic energy.
Q: How is the average force exerted by the ground on a person jumping from a height calculated?
A: By dividing the change in momentum or energy by the stopping distance.