1. Work and Power Problems
Use this PowerPoint to learn how to solve work and power problems. This is for the handout with only 6 questions.

2. Work Work = Force multiplied by Distance 𝑊=𝐹×𝑑
For work to be done, a force must be applied to an object and the object must move in the direction of the force
If the object remains stationary (doesn’t move) then no work has been done.
The unit for Work is Joules (J)

3. Problem 1: Renatta Gass is out with her friends
Problem 1: Renatta Gass is out with her friends. Misfortune occurs and Renatta and her friends find themselves getting a workout. They apply a cumulative force of 1080 N to push the car 218 m to the nearest fuel station. Determine the work done on the car.
W = F x d
W = 1080 N x 218 m
W = J

4. Problem 2: Hans Full is pulling on a rope to drag his backpack to school across the ice. He pulls with a force of 22.9 Newtons to drag his backpack a horizontal distance of 129 meters. Determine the work (in Joules) done upon the backpack.
This problem is just like Problem 1.
The correct answer is: J
Now go to the next slide and try number 4, yes I know I skipped number 3. Don’t worry, we’re going to go back.

5. Problem 4: Sheila has just arrived at the airport and is dragging her suitcase to the luggage check-in desk. She pulls on the strap with a force of 190 N to displace the suitcase 45 m to the desk. Determine the work done by Sheila on the suitcase.
This problem is just like Problem 1.
The correct answer is: 8550 J
Now let’s go back and look at number 3.

6. Notice that you don’t have a force, only a mass
Problem 3: Lamar Gant, U.S. powerlifting star, became the first man to deadlift five times his own body weight in Deadlifting involves raising a loaded barbell from the floor to a position above the head with outstretched arms. Determine the work done by Lamar in deadlifting 300 kg to a height of 0.90 m above the ground. (Force = mass * 9.8)
Notice that you don’t have a force, only a mass
Use the force formula above to calculate the force:
F = m * 9.8
F = 300 kg * 9.8
F = 2940 N
This is not the answer, just the force that you need calculate the work.
Continued on the next slide.

7. Problem 3: Lamar Gant, U.S. powerlifting star, became the first man to deadlift five times his own body weight in Deadlifting involves raising a loaded barbell from the floor to a position above the head with outstretched arms. Determine the work done by Lamar in deadlifting 300 kg to a height of 0.90 m above the ground. (Force = mass * 9.8)
W = F * d
W = 2940 * 0.90
W = 2646 J
Now you try Problem 6a

8. Problem 6: During the Powerhouse lab, Jerome runs up the stairs, elevating his 102 kg body a vertical distance of 2.29 meters in a time of 1.32 seconds at a constant speed. a. Determine the work done by Jerome in climbing the stair case.
This problem is just like Problem 3. (ignore the time)
The correct answer is: 2289 J

9. Power Power = Work divided by time 𝑃=𝑊÷𝑡
Power is directly related to work, so if the work increases then the power will also increase.
Power is indirectly related to time, so if the time increases then the power will decrease.
The unit for Power is Watts (W)

10. A lawnmower does 300 Joules of work in 3 minutes
A lawnmower does 300 Joules of work in 3 minutes. How much power does the mower have?
𝑃=𝑊÷𝑡
Time must be in seconds so… 3 minutes = 180 seconds
𝑃=300 𝐽÷180 𝑠
𝑃=1.67 𝑊

11. Now it’s your turn to work…
Complete the handout titled: Work and Power Practice Problems.
You should complete questions 1 – 10.
Number 9 is more difficult than the other problems, but I think you can do it. Remember that 1 kilometer = 1000 meters.
Turn in both handouts at the end of class.
Have a great weekend.