work, energy and power

• What is work done defined as?

  The product of force and distance
• What is the formula for work done in A-level physics?

  Work done = f x cosine(theta)
• What does 'f' represent in the work done formula?

  Force applied
• What does 'x' represent in the work done formula?

  Distance traveled
• What does 'theta' represent in the work done formula?

  Angle between force and displacement
• What should you do if given the angle complementary to theta?

  Subtract it from 90 degrees
• When is work done a maximum?

  When theta is equal to zero degrees
• What is the cosine of zero degrees?

  1
• What happens to work done when the angle is 90 degrees?

  Work done is 0 joules
• What is the unit for work done?

  Joule
• What is the base unit of the joule?

  kg m$s^{-2}$
• What is the formula for potential energy?

  Potential energy = mgh
• What does 'm' represent in the potential energy formula?

  Mass of the object
• What does 'g' represent in the potential energy formula?

  Acceleration due to gravity
• What is the value of 'g' on Earth?

  9.81 m/s$s^{-2}$
• How is work done related to potential energy when raising an object?

  Work done equals the change in potential energy
• What is the equation for kinetic energy?

  Kinetic energy = $\frac{1}{2}mv^2$
• What does 'v' represent in the kinetic energy formula?

  Final velocity of the object
• What principle is used to find the final speed of a ball rolling down a hill?

  Principle of conservation of energy
• What is the initial energy of the ball at the top of the hill?

  Potential energy = mgh
• What happens to the potential energy as the ball rolls down?

  It converts to kinetic energy
• How do you calculate the resistive force acting on the ball?

  By using the change in energy and work done
• What is the formula for power?

  Power = work done / time
• What is another equation for power involving velocity?

  Power = force x velocity
• How is mechanical efficiency calculated?

  Efficiency = (useful output energy / input energy) x 100
• What is the base unit of the joule?

  kg m$s^{-2}$
• What is the unit of efficiency?

  Percentage
• Why is potential energy equal to mgh when raising an object?

  Work done equals the weight times height
• What is the relationship between potential and kinetic energy when rolling a ball down a hill?

  Potential energy converts to kinetic energy
• What is the final speed of a ball rolling down a hill of height 5 meters?

  $v =$$\sqrt{2gh}$
• How do you calculate the speed of a ball at the bottom of a hill?

  Use $v =$$\sqrt{2gh}$
• What is the average resistive force acting on a ball with mass 2 kg reaching 8 m/s?

  4.9 newtons
• What is power defined as?

  Rate of work done or energy transfer
• What is the formula for power?

  Power = W / t
• How is mechanical efficiency calculated?

  Efficiency = (useful output / input) x 100
• What are the key concepts of work, energy, and power?

  • Work done: Product of force and distance
  • Energy: Cannot be created or destroyed
  • Power: Rate of work done or energy transfer
• What are the equations for potential and kinetic energy?

  • Potential energy: $PE =$$mgh$
  • Kinetic energy: $KE =$$\frac{1}{2}mv^2$
• What is the principle of conservation of energy?

  • Energy cannot be created or destroyed
  • Energy can only be transferred between forms
• What is the relationship between work done and energy change?

  • Change in energy equals work done on the system
• What factors affect the work done on an object?

  • Magnitude of the force applied
  • Distance moved in the direction of the force
  • Angle between force and displacement