work done and energy transfer

• What should you be able to describe by the end of the video?

  What's meant by work done
• What happens when a man pushes a box at constant velocity?

  The box experiences friction and temperature increase
• What energy transfer occurs when a man pushes a box?

  Chemical energy to thermal energy
• What is the scientific term for energy transfer when a force moves an object?

  Work
• How is work calculated?

  Work done = force × distance
• What must the distance be in relation to the force when calculating work?

  In the line of action of the force
• What unit is used to measure 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 the relationship between Newton meters and Joules?

  One Newton meter equals 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
• How do you calculate the work done when a force of 3,000 Newtons is applied over a distance of 15 meters?

  Work done = 45,000 Joules
• What happens to the kinetic energy of a car when it brakes?

  It is transferred to the thermal energy of the brakes
• What force acts on a person walking up stairs?

  The force of gravity
• If a person weighs 600 Newtons and 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 the process of energy transfer when work is done?

  • Force applied to move an object
  • Energy transferred from one store to another
  • Example: Chemical energy to thermal energy
• What are the key points to remember about calculating work done?

  • Work done = force × distance
  • Distance must be in the line of action of the force
  • Units: Joules or Newton meters
• What are some examples of work done in different scenarios?

  1. Pushing a box: Chemical to thermal energy
  2. Braking a car: Kinetic to thermal energy
  3. Walking up stairs: Chemical to gravitational potential energy