3.5 Power

• Power is defined as the rate of doing work or the **rate of energy transfer
• What is the formula for power in terms of work and time?

  $P =$$\frac{W}{t}$
• What is the definition of a watt (W) as a unit of power?

  1 joule per second
• Power is directly proportional to work
• What does the work-energy theorem state in relation to work and kinetic energy?

  Work equals change in KE
• What is the formula to calculate power using the work-energy theorem?

  P = \frac{KE_{f} - KE_{i}}{t}</latex>
• The formula for power is P = W/t
• Time in the power formula is measured in seconds
• 1 horsepower is equal to 746 watts.

  True
• Match the property with its definition:

  Power ↔️ Rate of doing work

  Work ↔️ Energy transferred

  Time ↔️ Duration of activity
• The work-energy theorem relates work to the change in kinetic energy.


  True
• Instantaneous power is the average power over a period of time.

  False
• What is the formula for average power?

  P_{avg} = \frac{W_{total}}{t_{total}}</latex>
• Instantaneous power provides detailed insights into the dynamics of a system at a specific moment in time.


  True
• Average power is better for understanding the overall energy usage of a system.

  True
• What are the units for power in the SI system?

  Watts
• One horsepower (hp) is equal to 746 watts.

  True
• Match the property with its definition:

  Power ↔️ Rate of doing work

  Work ↔️ Energy transferred

  Time ↔️ Duration of activity
• Using the work-energy theorem, power can be expressed as the change in kinetic energy divided by time
• What is the general formula used to calculate power in different contexts?

  $P =$$\frac{W}{t}$
• What unit is used to measure power?

  Watts
• Steps to calculate power using the formula P = W/t

  1️⃣ Identify the work done and the time taken

  2️⃣ Plug these values into the formula

  3️⃣ Calculate the power in watts
• Match the unit of power with its definition:

  Watt ↔️ 1 joule per second

  Horsepower ↔️ 746 watts
• What theorem states that the work done on an object equals the change in its kinetic energy?

  Work-Energy Theorem
• What are the key steps to calculate power in different contexts?

  Identify work, time, calculate power
• What mathematical tool is required to calculate instantaneous power?

  Calculus
• What is the formula for instantaneous power?

  $P =$$\frac{dW}{dt}$
• What is the formula for average power?

  P_{avg} = \frac{W}{t}</latex>
• What is the formula for power used in general problems?

  $P =$$\frac{W}{t}$
• Steps to calculate power in different contexts:

  1️⃣ Identify the work done and time taken

  2️⃣ Plug values into the formula P = W/t

  3️⃣ Calculate the power in watts
• Steps to apply the work-energy theorem to power

  1️⃣ Express work in terms of kinetic energy change

  2️⃣ Substitute the work-energy theorem into the power formula

  3️⃣ Calculate the final power
• If an object increases its kinetic energy by 500 joules in 10 seconds, its power is 50 watts.


  True
• If a person lifts a 20 kg object 2 meters, the work done is 392 joules
• Work is measured in joules.


  True
• What is the work done when a person lifts a 20 kg object 2 meters?

  392 J
• The formula for power is P = W/t
• Using the work-energy theorem, power can be expressed as P = ΔKE/t
• The formula for instantaneous power is P = dW/dt
• Average power is calculated as total work done divided by total time
• Instantaneous power requires the use of calculus