What Is Work?

Work is done when you apply a force over a distance so: WORK=FORCE X DIST. W=Fd

Remember. It has to move a distance to be considered work Remember!!! It has to move a distance to be considered work! Let’s try an example. Brett’s backpack weighs 30 N. How much work is done on the backpack when he lifts it 1.5 m from the floor to his back? Write the formula: W = F·d Fill in what we know: W= 30 N X 1.5 m Do the math: W = (30 N)(1.5 m) W = 45 J W = 45 Nm

To measure FORCE, we use a spring scale.

Is this work?

No, because there is no distance traveled.

Is this person doing work?

No. He is not exerting a force. The car is doing the work.

Are the horses doing work?

Yes. The horses are pulling forward and the wagon is moving forward.

Can you reduce the amount of work by using a simple machine?

No!!! You cannot reduce the work because you are still lifting the same box to the same height. The ramp makes the distance increase, so what happens to the force? WORK = FORCE X DISTANCE

THE FORCE GOES DOWN SO IT MAKES THE JOB FEEL EASIER BECAUSE YOU DO NOT HAVE TO DO AS MUCH PUSHING OR PULLING! THE WORK DONE IS STILL THE SAME

d= 5m F= 2 Newtons d= 1m F= 10 Newtons Work= F X d Work= F X d Work= 10 X 1 Work= 2 X 5 Work= 10 Joules Work= 10 Joules Work= 10 Nm Work= 10 Nm

All simple machines reduce force by spreading it out over a larger distance:

The response by a plant to sunlight by growing in that direction is called: PHOTOTROPISM

This response is called geotropism. The downward growth of roots is the plant’s response to gravity pulling water to the center of Earth. This response is called geotropism.

If a plant begins to wilt, it is because it is lacking turgor pressure.

A plant will become more firm and less wilted if water is added to it because: There will be a higher level of turgor pressure in the plant. Turgor pressure is when water inside the cell is pushing against the cell wall. Increase of water causes an increase of pressure, which makes the plant stand upright and not wilt.

Independent Variable is the variable that will stay the same regardless of the other variables. The independent variable will always be on the X-AXIS. Dependent Variable is the variable that change and be affected by other variables The dependent variable will always be on the Y-AXIS.

When we are talking about work: The formula for work is: W = F X d. The independent variable is: DISTANCE The dependent variable is: FORCE

Independent Variables: (X-AXIS) Dependent Variables: (Y-AXIS) Distance Force Angle Mass of Object