Work Done by Energy Transfer

• What happens when a man pushes a box at constant velocity?

  A forward force is applied against friction
• What does friction cause in the box during the push?

  The temperature of the box to increase
• What type of energy is transferred from the man's muscles to the box?

  Chemical energy to thermal energy
• What do scientists call the energy transferred when a force moves an object?

  Work
• How is work calculated according to the equation provided?

  Work done = force × distance
• What is the unit of work?

  Joule
• What does one Joule of work represent in terms of force and distance?

  One Newton moves an object by one meter
• What is equivalent to one Newton meter of work?

  One Joule
• If a man applies a force of 20 Newtons to move a box by 2 meters, what is the work done?

  40 Joules
• What happens to the kinetic energy store of a car when it brakes?

  It is transferred to the thermal energy store of the brakes
• During braking, if a force of 3,000 Newtons is applied and the car takes 15 meters to stop, what is the work done?

  45,000 Joules
• What does the weight of a person represent when walking up stairs?

  The force of gravity acting on the person
• If a person with a weight of 600 Newtons moves vertically 5 meters, what is the work done?

  3,000 Joules
• Why is only the vertical distance relevant when calculating work done against gravity?

  Because weight acts vertically downwards
• What is transferred from a person's chemical energy store when moving up stairs?

  Gravitational potential energy
• What is the relationship between work done, force, and distance?

  • Work done is energy transfer
  • Calculated as: Work = Force × Distance
  • Units: Joules (J) or Newton meters (N·m)
• What are the key points about work done in different scenarios?

  • Pushing a box: Chemical to thermal energy
  • Braking a car: Kinetic to thermal energy
  • Walking up stairs: Chemical to gravitational potential energy