Name: ____________________ Calculating Work and Power Scientists describe work as the movement of an object from one place to another. Like all things in science the amount or quantity of work can be calculated. To find the amount of work that is being done we can use this formula: W = F x d. The total amount of work is equal to the force applied times a distance. Power on the other hand is the rate at which work is done. We can calculate power using this formula: P = W/ t. The amount of power is equal to the amount of work divided by the time it takes to get the work completed. Remember to use your equation triangle to help solve simple equations. W F W d P t Cover the unit you are trying to find to get your formula. Finally, make sure you use the correct units. Work = Joules (J) Force = Newtons (N) Distance = Meters (m) Power = Watts (w) Time = Seconds (s) ______________________________________________________________________ W=Fxd P = W/ t F = W/ d W=Pxt D = W/ t t = W/ P Name: ____________________ Calculating Work and Power A. Fill in the blanks with the correct information. 1. 2. 3. 4. 5. 6. 7. 8. 9. The formula for work is: ____________ or _______________ The formula for power is: __________________________ To find force you must divide __________ by _____________. To find distance you must divide __________ by _____________. To find power you must divide __________ by _____________. To find time you must divide __________ by _____________. Distance is measured in ___________________. Work is measured in __________________. Power is measured in __________________. B. Find the formula, substitute your values, and then solve the equation. 1. F = 120 Newtons 3. Formula: _________________________________ d = 2 meters Substitution: ______________________________ W=? Answer with unit of measurement: _________________ 2. F = 5 Newtons Formula: _________________________________ W = 25 Joules Substitution: ______________________________ D=? Answer with unit of measurement: _________________ W = 100 Joules Formula: _________________________________ t = 20 seconds Substitution: ______________________________ P=? Answer with unit of measurement: _________________ Name: ____________________ Work and Power Equations I. Work Solve the following equations: 1. F = 20 N d=5m W = ________ 2. F = 6 N W = 36 J d = ________ 3. W = 120 J d = 20 m F = ________ 4. If a group of workers can apply a force of 500 Newtons to move a crate 20 meters, what amount of work will they have accomplished? 5. If 80 Joules of work were necessary to move a 5 Newton box, how far was the box moved? 6. How much work is done in holding your books, 1 meter off the ground while standing and waiting 10 minutes for your bus? II. Power Find the formula, substitute your values, and then solve the equation. 1. W= 200 Joules Formula: _________________________________ t = 25 seconds Substitution: ______________________________ P=? Answer with unit of measure: _________________ 2. P = 25 watts Formula: _________________________________ W = 1000 Joules Substitution: ______________________________ t=? Answer with unit of measure: _________________ 3. P = 170 watts Formula: _________________________________ t = 20 seconds Substitution: ______________________________ W=? Answer with unit of measure: _________________ 4. W = 50 J t = 10 s P = ________ 5. W = 500 J P = 25 W t = _______ 6. P = 40 W t=5s W = ________ 7. How much time is needed to produce 900 Joules of work if 120 watts of power is used? 8. If 230 W of power is produced in 10 seconds, how much work is done? 9. A crane does 300 Joules of work in 6 seconds. What power was used? CHALLENGE 10. A group of people move a large box that weighs 90 Newtons, 10 meters in 20 seconds, how much power was used? 11. A person weighing 200 N gets on an elevator. The elevator lifts the person 6 m in 8 seconds. How much power was used?