Name: Work- Simple Machine Quiz Study Guide 1.) What is one of the definitions for work? Moving something with a force, or when a force is applied through a distance or energy transfer through motion. 2.) What is the formula for work? Work= Force Distance 3.) What is the unit for work? Joule (N M) Simple Machines in General- 1.) What are the 6 types of simple machines? Inclined plane, lever, pulley, wheel and axle, screw & wedge 2.) What are the 2 basic types of simple of machines, of which all other simple machines are variations of? Inclined Plane & Lever 3.) In general, what do simple machines do? What is their purpose? Simple machines make work easier by reducing the force needed to do the same amount of work 4.) When we talk about work being easier, what do we mean by easier work? Less force required to do work 5.) A force applied by a machine to an object is the? a.) resistance force b.) effort force c.) force field 6.) A force applied to a machine by a person is the? a.) resistance force b.) effort force c.) force field Inclined Plane 1.) Draw an inclined plane in the space below and label the effort distance and resistance distance? 2.) An inclined plane reduces the force needed to lift an object by increasing the distance that force is applied. 3.) If it takes 45343 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 that is 4m long? a.) less than 45343 Joules b.) more than 45343 Joules c.) 45343 Joules Why? Simple machines never lower the amount of work, they only lower the force required to do the work, HOWEVER they can, because of friction, actually make more work
4.) If the force required to lift a barrel into the back of a truck was 124 Newtons, what would the force required to get the barrel into the back of the truck using a ramp that is 4m long? a.) less than 124 Newtons b.) more than 124 Newtons c.) 124 Newtons Why? Simple machines make work easier by reducing the force needed to move an object 5.) What did the experiment on page 4 prove? Using a simple machine reduces the force needed to move an object by increasing the distance of the force, HOWEVER does not change the total amount of work Lever 1.) Explain, in detail, how you would determine what class a lever is? The longer the arm of the lever to which force is applied, the less that force need be 2.) What happens to the force needed to move the object as you increase the effort arm by moving the fulcrum closer to the object. The force required to lift the weight will DECREASE 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.) Would machines with higher mechanical advantage would take more or less work to make something move? A.) more b.) Less c.) the same (because of Friction) 5.) True or False and explain- ALL LEVERS make work easier False- Third class levers do not make work easier, they give you increased speed. 6.) Label the effort, resistance and fulcrum in the pictures below an identify what class of lever it is.
Mechanical Advantage 1.) What is mechanical advantage? What does this tell us? (do not give formula, actually tell me what it is) The number of times a machine multiplies an effort force. It tells us how much easier a machine makes the work 2.) What is the difference between Ideal Mechanical Advantage and Mechanical Advantage. Ideal mechanical advantage does not take friction into account. 3.) Why do we look at the distance something travels rather than the force required with Ideal Mechanical Advantage? a.) looking at the distance is more accurate because it does not require force meters b.) looking at the distance eliminates friction c.) looking at the distance helps us measure the force d.) looking at the distance is easier because Mr. Strelick said so Pulley 1.) What are the three types of pulleys? Single moveable, single fixed and block & tackle 2.) How do you find the mechanical advantage of a pulley? Count how many sections of rope are supporting the weight. 3.) True or False and explain- ALL PULLEYS make work easier False, fixed pulleys do not make work easier, they only change direction of the force. 4.) Find the effort force required to lift the 300 N weight in the diagrams below. Summary 1.) 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. Single fixed pulley- change direction 3 rd class levers- give you increased speed 2.) Group the following words/phrases into 2 categories: Work in Work out Resistance Effort output input Work done TO THE machine Work in, Effort, input Work done BY THE machine Work out, Resistance, output
Wheel and Axle- 1.) The wheel and axle is most like which type of simple machine? a.) lever b.) inclined plane 2.) Which part of the wheel best represents the effort force? (large or small) Large Wheel 3.) what part of the wheel best represents the resistance force? Axle 4.) 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- It has a larger effort wheel (large wheel). When you increase the effort distance, you decrease the effort force. 5.) 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- Both amounts of work are the same due to the axles being the same. The 100cm wheel would just be easier because it travels a greater distance. The Screw- 1.) The screw is most like which type of simple machine? a.) lever b.) inclined plane 2.) What specifically are the arrows in the picture to the right pointing to? Threads Use the picture below to answer #3-5 3.) Which of the above screws (A or B) would require the greatest amount of force to drive into a piece of wood? a.) A b.)b Why There are less threads so there is less distance. There is MORE force required for the screw with less distance (threads) 4.) Which of the above screws (A or B) would be the easiest to drive into a piece of wood? a.) A b.)b Why There are more threads so there is more distance. Since the rule is the greater the distance the less the force, there is LESS force required for the screw with more distance(threads) 5.) Which of the above screws (A or B) would have the greatest mechanical advantage? a.) A b.)b
The Wedge.) The wedge is most like which type of simple machine? a.) lever b.) inclined plane 2.) What does the wedge do as it moves into a material? Separates them 3.) What are two examples of a wedge? Axe, Knife 4.) 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? Wedge B Why?- Wedge B has a greater distance (length) and the rule is when you increase the distance, you decrease the force (make work easier) Using Simple Machines 1.) What is a compound machine? A combination of 2 or more simple machines 2.) What is the formula for efficiency? 3.) Simple machines make work easier, but they actually make more work. Explain how this true, how can they make more work yet make the work easier? Simple machines make the work easier by decreasing the force needed to do something. They do this by increasing the distance that force is applied. Although the work is getting easier, the total amount of work is actually increasing due to friction. Power 1.) 1.) What is the definition of power The amount or rate of work done in a certain amount of time 2.) What is the formula for power? Power=work/time Units 1.) What is the unit for each of the following? Energy: Joules Work: Joules or Newton/Meters Power: Watts or Joules/second Mechanical advantage: no unit Efficiency: %
True or False and Explain! 1.) In general, simple machines make less work? False, simple machines make work easier but do not reduce the total amount of work needed. 2.) In general, simple machines make work easier? True, simple machines reduce the force needed to make something move. They do this by increasing the distance the force is applied 3.) Single moveable pulleys make work easier? True, It is the single FIXED pulley that does not make the work easier 4.) All types of levers make work easier? False- Third class levers do not make work easier, they give you increased speed. Calculations: Show your work 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. 1.) Exactly How much work would be required to lift this fridge of wigs without a machine? Force= 60 N Distance= 2 M Work = Force x Distance W= 60 Newtons x 2 M Work= 120 Joules 2.) 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? 120 joules- Using a lever with a M.A of 6 would only make the work easier, it would not change the total amount of work. 3.) Assuming no friction, how much force would be required to lift the fridge of wigs with a lever that has a mechanical advantage of 6? Since the M.A is 6, the force would be 6 times easier. Therefore the force would be 1/6 of the original force. Therefore the force would be 10 Newtons. 4.) 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 dishwasher without a lever would be 1000 N. MA = 25 FR = 1000N FE =? MA= F R or F E = F R F E MA F E =1000 N 25 F E = 40 N 5.) 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? Force= 50 N Distance= 8 M Work = Force x Distance W= 50 Newtons x 8 M Work= 400 Joules
6.) What is the mechanical advantage if a unicorn uses its horn as a lever, to open door using 300 N of force, which would normally take about 900N to open (without a simple machine). Resistance= 900 N Effort= 300 N M.A =? M.A = Resistance effort M.A = 900 N 300 N M.A = 3 7.)How much work is required to lift a bag of cat litter 2 meters, if the bag has a force of 40N. Force= 40 N Distance= 2 M Work = Force x Distance W= 40 Newtons x 2 M Work= 80 Joules 8.) 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 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? Resistance= 90 N Effort= 10 N M.A =? M.A = Resistance effort M.A = 90 N 10 N M.A = 9 9.) What is the Ideal Mechanical Advantage of a lever whose effort arm measures 55cm and whose resistance arm measures 5 cm? Resistance= 5 cm Effort= 55 cm I.M.A Lever =? I.M.A= Effort Arm Resistance Arm I.M.A = 55 cm 5 cm I.M.A = 11 10.) What is the Ideal Mechanical Advantage of an inclined plane that has a length of 400cm and a height of 50cm Resistance= 50 cm Effort= 400c m I.M.A Lever =? I.M.A= Effort dist(length) Resistance dist(height) I.M.A = 400 cm 50 cm I.M.A = 8 11.) What is the ideal mechanical advantage for the object below. Show your work Radius Wheel= 1.5cm Radius Axle= 0.3cm IMA= Radius of Wheel Radius of Axle IMA= 1.5cm 0.3cm IMA= 5 12.) What is the ideal mechanical advantage for the object below. Show your work Radius Wheel= 11cm IMA= Radius of Wheel Radius Axle= 3cm* Radius of Axle *its 3 because in the picture the 6cm represents the diameter IMA= 11 cm 3cm IMA= 3.67
13.) A mysterious green box is lifted onto the back of a truck that is 2.1M high. If it takes 500 Joules of work to do this without using a simple machine, what would be the efficiency of an inclined plane if the force required was 150N over a distance of 4 M? Work without machine= 500 Joules Work with machine= W=F D 150 N 4m = 600 Joules Work WITHOUT machine Work WITH machine 500 Joules x100 600 Joules 83.3% 14.) If you walk up the steps (distance of 4 meters) in 6 seconds, what is your power? Assume you have a force of 440 N Power=? Work= F x d =440N x 4m =1760J Time= 6 seconds Power= Work/Time 1760J 6 seconds 293,3 Watts 15.) What is the ideal mechanical advantage for a lever whose fulcrum is at 20cm? Resistance= 20cm Effort= 80cm I.M.A Lever =? I.M.A= Effort Arm I.M.A = 80cm Resistance Arm 20 cm I.M.A = 4 Formulas: Work= Force distance Efficiency= Work (out) or F (resistance) X D (resistance) X 100% Work (in) F (effort) X D (effort) Power= Work Time MA = Resistance Force or F R Effort Force F E I.M.A = Effort Distance or D E Resistance Distance D R I.M.A(wheel & Axle) =Radius of wheel or Diameter of wheel Radius of axle Diameter of axle