Work done and Energy Transfer

• What is meant by work done in physics?

  Work done is a measure of energy transfer when a force moves an object.
• How is work done calculated?

  Work done = Force (in Newtons) × Distance (in meters)
• What is the unit of work done?

  The unit of work done is the joule (J).
• What does it mean when a force of one newton moves an object by one meter?

  One joule of work is done when a force of one newton moves an object by one meter.
• What is the relationship between newton meters and joules?

  • One newton meter of work equals one joule.
• How do you calculate the work done when a force of 20 newtons moves a box by 2 meters?

  The work done is 40 joules.
• What happens to the kinetic energy of a car when it brakes?

  The kinetic energy is converted to thermal energy in the brakes, slowing the car down.
• If a force of 3,000 newtons is applied to the brakes of a car over a distance of 15 meters, what is the work done?

  The work done is 45,000 joules.
• What is the work done when a person with a weight of 600 newtons moves vertically up 5 meters?

  • Work done = Weight × Vertical Distance
  • Work done = 600 N × 5 m = 3,000 J
• Why is only the vertical distance relevant when calculating work done against gravity?

  Only the vertical distance is relevant because weight acts downwards.
• What energy transfer occurs when a person walks up stairs?

  • Chemical energy store in the person is transferred to the gravitational potential energy store.