Solved Examples: Finding Average Power for AP Physics 1

📚 Quick Study Guide

• ⏱️ Average power is the rate at which work is done or energy is transferred.
• 🧮 The formula for average power is: $P_{avg} = \frac{W}{\Delta t}$, where $P_{avg}$ is the average power, $W$ is the work done, and $\Delta t$ is the time interval.
• 💪 Work done can also be expressed as $W = Fd\cos(\theta)$, where $F$ is the force, $d$ is the displacement, and $\theta$ is the angle between the force and displacement vectors.
• ⚡ Therefore, average power can also be written as $P_{avg} = Fv\cos(\theta)$, where $v$ is the average velocity.
• 📐 Remember to use consistent units: Watts (W) for power, Joules (J) for work, seconds (s) for time, Newtons (N) for force, and meters (m) for distance.

Practice Quiz

1. A 60 W light bulb is left on for 1 minute. How much energy does it consume?
   1. 360 J
   2. 60 J
   3. 3600 J
   4. 600 J
2. A force of 10 N is applied to an object, causing it to move 2 meters in 4 seconds. If the force is in the same direction as the displacement, what is the average power?
   1. 5 W
   2. 20 W
   3. 8 W
   4. 0.8 W
3. A motor lifts a 5 kg object 10 meters in 2 seconds. What is the average power output of the motor? (Assume $g = 9.8 m/s^2$)
   1. 245 W
   2. 49 W
   3. 98 W
   4. 196 W
4. An athlete does 300 J of work in 6 seconds. What is the athlete's average power output?
   1. 1800 W
   2. 50 W
   3. 306 W
   4. 0.02 W
5. A car engine provides a force of 2000 N to move the car at a constant speed of 15 m/s. What is the power developed by the engine?
   1. 3000 W
   2. 30000 W
   3. 133.3 W
   4. 2015 W
6. A pump lifts 50 kg of water to a height of 20 meters in 10 seconds. What is the average power of the pump? (Assume $g = 9.8 m/s^2$)
   1. 980 W
   2. 9800 W
   3. 100 W
   4. 1000 W
7. If the power output of a machine is 500 W, how much work can it do in 5 seconds?
   1. 100 J
   2. 2500 J
   3. 505 J
   4. 495 J