You are Stronger than you seem, Braver than you believe, and Smarter than you think you are. Use the gifts that you have been given.

O.K., LET’S GET SOME WORK DONE! BUT, WAIT! WHAT IS WORK?

WORK IN PHYSICS HAS TO DO WITH THE THE EXCANGE OF ENERGY BETWEEN TWO OR MORE OBJECTS. A FORCE HAS TO BE APPLIED, AND SOMETHING HAS TO MOVE IN THE DIRECTION OF THE APPLIED FORCE. WORK EQUALS THE FORCE TIMES THE DISTANCE THE FORCE IS APPLIED. W = F x d

THE UNITS FOR WORK ARE JOULES. SINCE W = F x d AND F IS MEASURED IN NEWTONS, 1 JOULE = 1 NEWTON METER OR SINCE 1 NEWTON = 1 kg m/sec 2 1 JOULE = 1 kg m 2 /sec 2 SO, YOU COULD THINK OF ONE JOULE AS THE FORCE NECESSARY TO ACCELERATE 1 kg OF MASS 1 m/sec 2 APPLIED OVER 1 m.

SORT OF COMPLICATED, BUT WHAT YOU REALLY NEED TO KNOW IS THAT THE AMOUNT OF WORK DEPENDS ON TWO FACTORS: 1)THE AMOUNT OF FORCE APPLIED 2)THE DISTANCE OVER WHICH THE FORCE IS APPLIED SO, WORK IS A FORCE ACTING OVER A DISTANCE, AND WE MEASURE IT IN JOULES.

ONE JOULE OF WORK IS DONE WHEN ONE NEWTON OF FORCE MOVES SOMETHING FOR ONE METER. AN EXAMPLE WOULD BE LIFTING AN APPLE WEIGHING 1 NEWTON FROM YOUR WAIST OVER YOUR HEAD. LET’S DO A SIMPLE CALCULATION.

WORD OF CAUTION: THE APPLIED FORCE HAS TO BE IN THE SAME DIRECTION AS THE RESULTING MOTION. IF IT IS AT RIGHT ANGLES TO THE MOTION, THEN THAT FORCE DID NOT DO ANY WORK. SO, IT IS THE FORCE COMPONENT IN THE DIRECTION OF MOTION THAT DOES THE WORK.

To climb stairs you have to work against gravity. The force of gravity on you is your weight so you have to lift your weight over each step, a distance of D. Let’s see how much work and power it takes to climb a flight of stairs. Find your weight in Newtons. If you know it in pounds, convert it to N by multiplying your weight by 4.45 N/pound. If you have a kilogram scale, multiply your mass by 9.8 m/sec 2 to get N. This is the F for your equation. Find the distance up you climb. This is not the linear the distance you walk from the bottom step to the top step. It is the sum total of the step heights. This is your D. The Work is simply the product of F times D.

LET’S LOOK AT THE WORK EQUATION AGAIN. W = F x d THERE IS NOTHING ABOUT TIME IN THAT EQUATION. IT DOES NOT MATTER HOW FAST OR SLOW YOU DO THE WORK, IT’S STILL THE SAME AMOUNT OF WORK. OF COURSE, IF YOU DO IT REALLY SLOW, YOU MIGHT BE ACCUSED OF BEING LAZY.

THERE IS AN EXPRESSION THAT TAKES INTO ACCOUNT TIME. POWER IS THE RATE AT WHICH WORK IS DONE, AND THE EQUATION IS: P = W/t SO, POWER IS WORK DIVIDED BY TIME. THE UNITS FOR POWER ARE WATTS. A WATT IS 1 JOULE/sec. Named for the Scottish engineer, James Watt

ANOTHER UNIT OF POWER IS HORSE POWER, hp. THIS UNIT IS BASED ON THE POWER THAT AN AVERAGE FARM HORSE WOULD PUT OUT. 1 hp = 746 watts SO, HOW LONG DID IT TAKE YOU TO CLIMB THE STAIRS? WHAT IS YOUR HORSE POWER RATING? Thanks to: