4.7 Work, energy, and power

• Work is calculated using the formula W = Fd cosθ
• Work is a scalar quantity.

  True
• Electrical energy is carried by moving electric charges
• What is the definition of the Joule (J) in terms of force and distance?

  1 N moving 1 m
• What is power defined as?

  Rate of energy transfer
• Match the type of power with its definition:

  Average Power ↔️ Total work divided by time

  Instantaneous Power ↔️ Power at a specific instant
• If the angle between force and displacement is 0°, the work done is positive.


  True
• The work-energy theorem states that work done equals the change in kinetic energy.
• An object of 2 kg moving at 5 m/s has 50 J of work done on it. What is its final kinetic energy?

  75 J
• The formula for the work-energy theorem is W = ΔKE = KE_f - KE_i
• Arrange the following actions based on their effect on kinetic energy:

  1️⃣ Positive work done

  2️⃣ No work done

  3️⃣ Negative work done
• A 2 kg object initially moving at 5 m/s has 50 J of work done on it. Its final kinetic energy is 75
• The Joule is the SI unit of work, equivalent to 1 Newton meter.


  True
• Match the type of energy with its definition and example:

  Kinetic Energy ↔️ Energy of motion, a moving car

  Potential Energy ↔️ Stored energy due to position, a ball held high

  Thermal Energy ↔️ Energy associated with temperature, heat from a fire

  Chemical Energy ↔️ Energy stored in chemical bonds, food digestion
• What is the formula for calculating power?

  P = W/t
• There are two types of power: average power and instantaneous power.
• Arrange the following factors based on their effect on work done:

  1️⃣ Greater magnitude of force

  2️⃣ Larger distance moved

  3️⃣ Angle between force and displacement
• A force of 50 N pushes a box 3 meters at an angle of 30°. The work done is approximately 129.9 J.
• What is work done when a force causes an object to move a distance?

  Energy transfer
• What is the SI unit of work?

  Joule (J)
• Match the type of energy with its definition:

  Kinetic Energy ↔️ Energy of motion

  Potential Energy ↔️ Stored energy due to position

  Thermal Energy ↔️ Energy of random atom motion
• What happens to an object's energy when positive work is done on it?

  Energy increases
• Work is a vector quantity.

  False
• Power is calculated using the formula P = W/t
• What is the unit of power?

  Watt (W)
• What is the work done when a force of 50 N pushes a box 3 m at an angle of 30°?

  129.9 J
• What happens to kinetic energy when negative work is done on an object?

  Decreases
• What does the work-energy theorem state?

  Work equals change in KE
• In the work-energy theorem, W represents the work done in Joules.


  True
• What happens to kinetic energy when positive work is done on an object?

  It increases
• What is the formula for calculating work when a force moves an object a distance?

  W = Fd cosθ
• Is work a scalar or vector quantity?

  Scalar
• Positive work increases energy, while negative work decreases
• The unit of power is the Watt, equivalent to 1 Joule per second.


  True
• What formula is used to calculate work done when a force is applied at an angle to the direction of movement?

  W = Fd cosθ
• What happens to work done if the angle between the force and displacement is 90°?

  Work is zero
• What is the relationship between work done and the change in kinetic energy according to the work-energy theorem?

  W = ΔKE
• The work-energy theorem is expressed as W
• Match the type of work done with its effect on kinetic energy:

  Positive work ↔️ Increases kinetic energy

  Negative work ↔️ Decreases kinetic energy

  No work done ↔️ Kinetic energy remains constant
• In the kinetic energy formula, 'm' represents the mass