MATH - SCIENCE INTEGRATION

Calculating Work

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

Work Equation

 The equation to solve work problems looks like this: work = force x distance  or   W = F x d The SI unit for force is newton (N). The SI unit for distance is meter (m). The SI unit for work is joule (J). 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.

Steps for Calculating Work

 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.
 Make sure that all of your numbers have the correct SI unit label. Always recheck your answers. The next page will give you some sample problems with the answers.

Sample Work Problem #1

 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?

• Equation
 W = F x d = (27.5N) (12.3m) =  ?

 W =  338.25J Did you get it correct?  Try another one!

Sample Work Problem #2

 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.

• Equation
 F =  W  =  55,000J  =  ?         d           25m

 F = 2200J Think you're pretty good at this?  Work one more sample problem before you complete the practice problems.

Sample Work Problem #3

 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?

• Equation
 You need to rearrange the work formula to look for distance: d=  W  = 1762.2J  =        F      489.5N