UNITS OF WORK

"I did more work than you!"
"No way, I did more!"

The equation to solve work problems looks like this:
work = force x distance or W = F x d
Now let's look at the steps for calculating work.
If you need some review on calculating one step equations, click
on the link below.

We will continue to use the same procedure to solve work
problems as we have when working other physics problems.
Remember to continue to work in a step by step
manner by writing each step out.

Problem:
A fork lift moves 34m carrying a
1023N box across the warehouse floor.
How much work is done by the fork lift.

Step 1:
Write down the equation
needed to solve the problem.

W = F x d

Step 2:
Insert all known
measurements into the equation.

W =
(1023N)(34m)

Step 3:
Solve. Carefully enter
numbers into your calculator.

W = 34,782 J
The forklift does 34,782J of
work.

The next page will give you some sample problems with the answers. 
Remember as you solve the following problems to keep
following the steps shown on the previous page.

Problem #1:
How much work is done by a
person who uses a force of
27.5N to move a grocery
buggy 12.3m?

Problem #2:
55, 000J of work is
done to move a rock
25m. How much force
was applied?

Many work problems give you the amount of work done, but
want you to solve for distance or force.
In that case the work formula can be rearranged to look for the other variables. In this problem, we are looking for force, so the equation must be rearranged. 
Let's try a problem where
distance is the unknown.

Problem #3:
You and 3 friends apply a
combined force of 489.5N to
push a piano. The amount of
work done is 1762.2J. What
distance did the piano move?

Get your paper, pencil, and calculator ready for some work
practice problems! Make sure to label all numbers with SI units
and show all of your work.
Practice Problems:
1. Calculate the amount of work done when moving a 567N crate a
distance of 20 meters.
2. A fallen tree is lifted 2.75 meters. How much work is done? 3. If it took a bulldozer 567.6 joules of work to push a mound of dirt 30.5 meters, how much force did the bulldozer have to apply? 4. A frontend loader needed to apply 137 newtons of force to lift a rock. A total of 223 joules of work was done. How far was the rock lifted? 5. A young boy applied a force of 2,550 newtons on his St. Bernard dog who is sitting on the boy's tennis shoes. He was unable to move the dog. How much work did he do trying to push the dog? 6. If it takes 68 joules of work to push a desk chair across a floor, what force would be needed? 7. If a long distance runner with a weight of 596.82 newtons does 35,674.7 joules of work during a portion of a race, what distance will she cover during that portion? 8. If a weight lifter raises a barbell with a mass of 125.7 grams doing 5,023 joules of work, what distance did he move the barbells? Remember that you need a force, not a mass. You must first calculate the force in order to complete your solution. HINT: Weight is a force. Weight on earth is determined by multiplying an object's mass times earth's gravitational pull (9.8m/s^{2} ). 9. Children are sled riding on a hill. One little girl pulls her sled back up the hill and does 379.5 joules of work while pulling it back up the 17.3 meter hill. What amount of force did she exert on the sled? 10. A large semitruck is moving a house from one lot to another. The amount of force required to move the house horizontally a distance of 73.2 meters is 3,500 newtons. How much work will be done on the house? 