4.) What do we mean when we say machines make work easier? (force vs. distance)

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1 Name: Simple Machines Study Guide Force and Work- 1.) To be considered work, you have to have a and a through which the force acts. 2.) What is the formula for work? What is the unit for work? 3.) What does something have to do to be considered a machine? 4.) Decide if work is done for each of the following: (Are the requirements for WORK met?) a. Someone is sitting on a cushion on the floor. Work or NO work b. A baseball is hit into the bleachers. Work or NO work c. Ms. Jarrett holds a doorstop in one place to show you an example of a wedge. Work or NO work d. A little girl is pushed on a swing. Work or NO work Simple Machines Basics 1.) What are the 2 basic types of simple of machines, of which all other simple machines are variations of? Also list the other simple machines in the correct category under the heading. & 2.) In general, what do most simple machines do? 3.) Do simple machines make less work? Explain. 4.) What do we mean when we say machines make work easier? (force vs. distance) 5.) A force applied by a machine to an object is the? a.) resistance force b.) effort force c.) force field d.) Jedi force 6.) A force applied to a machine by a person is the? a.) resistance force b.) effort force c.) force field d.) Jedi force 7.) Simple machines make work easier, however there are 2 exceptions to this rule. What are the exceptions, and in each case, what is the advantage each machine gives us? 1. 2.

2 Inclined Plane 1.) An inclined plane decreases the needed to lift an object by the distance that force is applied. 2.) In general, less force = distance, and more force = distance 3.) If the force required to lift a barrel into the back of a truck was 124 Newtons without a simple machine, what would the force required to get the barrel into the back of the truck using a ramp? (Think in general, you don t have enough info to calculate.) a.) less than 124 Newtons b.) more than 124 Newtons c.) 124 Newtons 4.) Inclined planes can increase the amount of work done due to. 5.) If it takes joules of work to lift a barrel into the back of a truck without using a simple machine, how much work would be required to get the barrel into the back of the truck using a ramp? (Think in general again, and CONSIDER FRICTION) a.) less than Joules b.) more than Joules c.) Joules Lever 1.) A lever turns on a fixed point, called the. 2.) Other than multiplying a force, what else can levers do? 3.) Explain how you would determine what class a lever is. (Look where and be what?) 4.) What happens to the force needed to move an object as you increase the length of effort arm? 5.) What would happen to the force required if you decreased the length of the effort arm? 6.) True or False and explain- ALL LEVERS make work easier. 7.) Label the effort, resistance and fulcrum in the pictures below an identify what class of lever it is.

3 Pulley 1.) Pulleys can a force or change is. 2.) What are the three types of pulleys? 3.) How do you find the mechanical advantage of a block and tackle? 4.) True or False and explain-all PULLEYS make work easier. 5.) How does the distance of the string you pull compare to the distance the weight is lifted when using a block and tackle system? 6.) What is the MA of a single fixed pulley? single movable pulley? 7.) Find the effort force required to lift the 300 N weight in the diagram. Simple vs. Compound Machines (mentioned in machines reading) 1.) What makes something a compound machine instead of a simple machine? 2.) Label each machine with S for simple and C for compound. a. scissors d. pry bar b. ramp e. bicycle c. single fixed pulley f. shovel 3.) List 3 of your own examples of compound machines. (Remember: Machines help make WORK easier. Mechanical Advantage Basics 1.) Mechanical advantage is how much the machine your force. 2.) What does it mean about a machine if it has a mechanical advantage of 1? 3.) Would Machines with higher mechanical advantage would take more or less effort force to make something move? A.) more b.) Less c.) the same

4 4.) Would machines with higher mechanical advantage would take more or less work to make something move? A.) more b.) Less c.) the same 5.) If you have a choice between a machine with a MA of 4 and a machine with an MA of 6, which machine would it make more sense to use? Wheel and Axle- 1.) Object with larger radius=, object with smaller radius= 2.) What would be easier (take less force) to turn and why: An axle with a diameter of 10cm using a 100cm wheel An axle with a diameter of 10cm using a 50cm wheel Why?- 3.) What would require the least amount of work to turn and why: An axle with a diameter of 10cm using a 100cm wheel An axle with a diameter of 10cm using a 50cm wheel Why?- 4.) Calculate the IMA for the following machines. Show your work. The Screw- 1.) Which of the screws to the right (A or B) would require the greatest amount of force to drive into a piece of wood? Why? 2.) Which of the screws to the right (A or B) would be the easiest to drive into a piece of wood? Why? 3.) Which of the above screws (A or B) would have the greatest mechanical advantage? 4.) What is a specific advantage we discussed of using a screw instead of an inclined plane? (Think staircases)

5 The Wedge 1.) What does the wedge do as it moves into a material? 2.) Of the two wedges to the right, which do you think would require the least amount of force if you wanted to separate those objects 8cm and why? 4.) What is a major difference between the wedge and an inclined plane? 3.) Measure and calculate the IMA of the wedges. Calculations: Show your work! You will be given the following on your test: Work = force x distance Length of slope IMA wedge = FR DE Height or thickness Radius wheel MA x FE IMA x DR IMA wheel and axle = Radius axle MA = Resistance Force I.M.A = Effort Distance Effort Force Resistance Distance 1.) A clown is trying to lift a refrigerator full of wigs a height of 2M. It would take him a force of 60 Newtons to lift the fridge without a simple machine. a.) Exactly How much work would be required to lift this fridge of wigs without a machine? b.) Assuming no friction, how much work would be required to lift the fridge of wigs with a lever that has a mechanical advantage of 6? c.) Assuming no friction, how much effort force would be required to lift the fridge of wigs with a lever that has a mechanical advantage of 6?

6 2.) What is the force needed to lift a magic school bus if you use a lever with a mechanical advantage 25. The force required to lift the magic school bus without a lever would be 1000 N. 3.) How much work is being done by a penguin pushing a purple piano with a force of 50 N up a ramp that is 8 meters long? 4.) What is the mechanical advantage if a unicorn uses its horn as a lever to open a door 2 feet wide using 300 N of force, which would normally take about 900N to open without a simple machine? 5.)How much work is required to lift a bag of cat litter 2 meters, if the bag has a force of 40N? 6.) Melvin the mighty monkey is trying to get a big bag of bananas into his tree house. It takes 90 Newtons of force to lift into a tree without using a simple machine. He then makes the work easier by putting a ramp that is 10 feet long up to his tree house, which allows him to move the bag of bananas with 10 Newtons of force. What is the Mechanical Advantage of this inclined plane? 7.) What is the Ideal Mechanical Advantage of a lever whose effort arm measures 55cm and whose resistance arm measures 5 cm? 8.) What is the Ideal Mechanical Advantage of an inclined plane that has a length of 400cm and a height of 50cm? 9.) What is the ideal mechanical advantage for a lever whose fulcrum is at 20cm?