1. The Physics of Life I Force, Motion, & Work 7.7 Force motion and energy. The student knows that there is a relationship among force, motion & energy. The student is expected to: A.contrast situations where work is done with different amounts of force to situations where no work is done such as moving a box with a ramp and without a ramp or standing still. Famigletti/ PAP 7 th

2. Blue slides Contain information on your notes sheet!!

3. Background A.contrast situations where work is done with different amounts of force to situations where no work is done such as moving a box with a ramp and without a ramp or standing still. 1. Force- measured in newtons Named after Issac Newton who came up with the laws of Motion 2. Newtons Laws of Motion – 1 st Law of inertia INERTIA- Resistance to change Objects at rest will not begin to move until an unbalanced force acts on them Objects in motion will not stop moving until an unbalanced force acts on them – 2 nd Law: Acceleration Force = Mass x acceleration You will use this equation in 8 th grade – 3 rd Law: Action/ Reaction – for every action there is an equal and opposite reaction

4. Friction- a force that resists motion of an object (ex: rough surface). Air resistance is the frictional force of air that pushes against an object Gravity- a force that attracts all objects toward each other. The force of gravity on earth NEVER changes! Forces you already know…

5. Balanced & Unbalanced Forces Balanced Forces There is no change in motion All forces acting on an object are equal Equilibrium is achieved Unbalanced Forces All forces acting on an object are not equal Change in motion occurs to reach equilibrium All forces move toward equlibrium

6. Forces related to basic processes Plate movement (tectonics) Weather Blood flow in the body Turgor Pressure Jet propulsion Emergence of seedlings Erosion Add a sketch, diagram or definition to each of these terms to help you remember!!

7. Plate Movement Natural forces such as volcanoes, earthquakes, tsunamis and mountain building are a result of the movement of the earth’s tectonic plates. The plates move and shift because of unbalanced forces, typically pressure and heat.

8. Weather Occurrences Unbalanced forces of heat and pressure cause updrafts which lead to thunderstorms, and in severe cases tornados and hurricanes http://episodeinfo.com/tvshows/?tag=tornado http://www.ng.mil/news/archives/2010/05/051910-Katrina.aspx

9. Gravity Many basic movements are the result of the force of gravity. Erosion, landslides, Glacial abrasion is the result of gravity pulling the water and crust of our planet closer to its core http://nasadaacs.eos.nasa.gov/articles/2007/2007_landslides.html akulpillai.com

10. WORK http://www.abettercrane.com/

11. Work Work is done when a force moves an object over a distance. In science, a force is a push or pull. Work is calculated using the formula: W = F∙d – Where: W = work measured in Joules (J) F = force measured in Newtons (N) d = distance measured in meters (m)

12. Calculating Work Problem: Problem: – If a force of 5N is applied to an object for 4m, how much work was done on the object. Solution: Solution: 1. What do you know? What are you trying to find? d = 4 m F = 5 N W =?? 2. Substitute into the calculation to find what you are looking for… The force done on the object is 20J

13. Work Equation Triangle W FD Work = Force x Distance Distance = Work / Force Force = Work/ Distance **** always remember to convert distance to meters!!!!****

14. Accomplishing Work In science, work is done when BOTH of the following are satisfied: 1. A force is applied to an object. A cyclist coasting downhill is not work. No force is being applied by the cyclist to the bike. The force is equal to zero. 2. The object moves. A person pushing against a solid wall is not work. The wall does not move. The distance the object is moved is equal to zero. If either of these doesn’t happen work is equal to zero.

15. Work or Not?

16. Work it out! 1. A bodybuilder pushes on a 747 jumbojet airplane as hard as he can, but can’t budge it. Work = f? x d (0) Work = 0 J 5. A kindergartener punches a worm half a meter into the air. He hits with a force of 37 N. Work = 37n x.5m Work= 18.5 J 6. A girl loses control of her bike, rolling with a force of 950 N, and smashes into her 500 newton big sister, throwing her to the ground 3 m away. The bike’s wheels are 70 cm. – Remember the laws of motion! – Work = (Fa – Fb) x D W= (950-500) x 3 W= 450n X 3m = 1350 J 7. A crane picks up a 5 year-old minivan. It lifts it 16 meters into the air. It performs 65,600 J of work. How strongly is the crane pulling? Force = W / D 65,600/ 16 = 4100 n

17. Work can not be reduced, but can be made easier by simple machines. – Simple machines trade force for distance. As distance increases, the less amount of force is needed to complete work. – Simple machines include: Pulleys, inclined planes, wedges, levers, wheels & axels Simple Machines and Work

18. – The movement of an inclined plane is a slide or ramp. – It functions by increasing the distance over which work is done, thereby reducing the force required to accomplish the work. Examples of an incline plane include: – Mountain roads – Loading ramps – Cork screw / metal bolts – stairs Inclined Planes

19. Simple machines can be found everywhere.. Even in our bodies! Musculoskeletal system may be thought of as a series of simple machines http://www.whitemountainpt.com/html/faqs.html

20. Levers Levers are the most common simple machines in the body Humans move through a system of levers Lever - a rigid bar that turns about an axis of rotation or a fulcrum – Axis/Fulcrum - point of rotation about which lever moves

21. As a lima bean seedling starts to grow into the soil the root tip is able to push through the soil because it acts as a -- A.Wheel B.Pulley C.Gear D.Wedge Simple Machines in Plants!! D. Wedge!! The ends of roots are pointed to focus all of the plant’s force onto one tiny tip! Smart!!