4.7 Work, energy, and power

• The law of conservation of energy states that energy can be created but not destroyed.

  False
• What is the formula for kinetic energy?

  $KE =$$\frac{1}{2}mv^{2}$
• Work in physics is the transfer of energy when a force causes a displacement
• Energy is the ability to do work or cause change
• Match the energy form with its description:

  Potential Energy ↔️ Stored energy due to position

  Chemical Energy ↔️ Energy stored in chemical bonds

  Nuclear Energy ↔️ Energy from nuclear reactions
• What happens to kinetic energy when an object slows down?

  Converts to thermal energy
• Match the energy form with its description:

  Kinetic Energy ↔️ Energy of motion

  Potential Energy ↔️ Stored energy due to position

  Thermal Energy ↔️ Energy from heat
• What type of energy is produced in a nuclear power plant?

  Nuclear energy
• What is the definition of power in physics?

  Rate of energy transfer
• What is the formula for work in physics?

  W = F \cdot d \cos \theta</latex>
• Energy forms can be converted into one another without loss of total energy in a closed system

  True
• What does the law of conservation of energy state?

  Total energy remains constant
• The energy of motion is called kinetic energy.
• How is power defined in physics?

  Rate of energy transfer
• One watt is equivalent to one joule per second.


  True
• What is the definition of work in physics?

  Energy transfer by force
• What does the law of conservation of energy state about the total energy in a closed system?

  Remains constant
• What is the formula for potential energy?

  $U =$$mgh$
• Energy conversion in a closed system results in a net increase in total energy.

  False
• What is power in physics defined as?

  Rate of energy transfer
• If a machine lifts a 500 kg object 10 meters in 25 seconds, what is the work done?

  $49,000 \text{ J}$
• What is the formula for calculating work when the force and displacement are at an angle?

  $W =$$Fd\cos\theta$
• The kinetic energy of a 2 kg object moving at 3 m/s is $9 \text{ J}$
• Potential energy is the stored energy an object possesses due to its position
• What is work in physics defined as?

  Transfer of energy
• What is power in physics defined as?

  Rate of energy transfer
• Potential energy is calculated using the formula $PE =$$mgh$


  True
• Match the key concept with its definition:

  Work ↔️ Transfer of energy when a force causes displacement

  Force ↔️ Push or pull acting on an object
• What is kinetic energy defined as?

  Energy of motion
• The law of conservation of energy states that the total energy in a closed system remains constant
• What type of energy is produced when a car slows down due to friction?

  Thermal energy
• The law of conservation of energy states that the total energy in a closed system remains constant
• Order the following energy conversion examples from start to finish:

  1️⃣ Chemical energy in fuel is burned

  2️⃣ Thermal energy is produced

  3️⃣ Electrical energy is generated

  4️⃣ Kinetic energy powers a motor
• One watt is equal to one joule per second


  True
• Work is measured in joules


  True
• What happens to the kinetic energy of a car as it slows down?

  Converts to thermal energy
• Kinetic energy is converted to thermal energy through friction in a slowing car.


  True
• What type of energy does a compressed spring have?

  Potential energy
• Power is measured in watts.
• What is the formula to calculate work done when a force acts at an angle?

  $W =$$Fd\cos\theta$