2024 8th Grade Science Unit 1 Test Review Solutions PDF

‭Knowledge‬‭Questions-‬‭ANSWERS‬ ‭For‬ ‭SOLUTIONS-‬‭Simple‬‭Machines‬‭Application‬‭Questions‬ 1‭.‬ ‭When‬‭using‬‭a‬‭can‬‭opener,‬‭what‬‭input‬‭force‬‭is‬‭involved?‬ ‭What‬‭is‬‭the‬‭output‬‭force?‬ ‭Input/effort‬‭is‬‭the‬‭force‬‭from‬‭the‬‭hand.‬‭Output/load‬...

‭Knowledge‬‭Questions-‬‭ANSWERS‬ ‭For‬ ‭SOLUTIONS-‬‭Simple‬‭Machines‬‭Application‬‭Questions‬ 1‭.‬ ‭When‬‭using‬‭a‬‭can‬‭opener,‬‭what‬‭input‬‭force‬‭is‬‭involved?‬ ‭What‬‭is‬‭the‬‭output‬‭force?‬ ‭Input/effort‬‭is‬‭the‬‭force‬‭from‬‭the‬‭hand.‬‭Output/load‬‭is‬‭the‬‭resistance‬‭by‬‭the‬‭lid‬‭of‬‭the‬‭can.‬ ‭.‬ ‭Name‬‭the‬‭six‬‭simple‬‭machines‬‭and‬‭give‬‭an‬‭example‬‭of‬‭each.‬ 2 ‭Pulley‬‭-‬‭flagpole,‬‭sailboat‬ ‭Lever‬‭-‬‭class‬‭1:‬‭teeter‬‭totter,‬‭class‬‭2:‬‭wheelbarrow,‬‭class‬‭3:‬‭hockey‬‭stick‬ ‭Wheel‬‭and‬‭Axle‬‭-‬‭bike‬‭wheels,‬‭wrench,‬‭cranks‬ ‭Inclined‬‭plane‬‭-‬‭ramp,‬‭ladder,‬‭staircase‬ ‭Wedge‬‭-‬‭knife,‬‭doorstop,‬‭axe‬‭blade‬ ‭Screw‬‭-‬‭Screw!‬‭Spiral‬‭staircase.‬  ‭3.‬ ‭Draw‬‭the‬‭force‬‭diagrams‬‭for‬‭a‬‭box‬ ‭being‬‭pushed‬‭up‬‭an‬‭incline.‬ ‭.‬ ‭What‬‭does‬‭mechanical‬‭advantage‬‭mean?‬‭What‬‭is‬‭the‬‭difference‬‭between‬‭IMA‬‭and‬‭AMA?‬ 4 ‭Mechanical‬‭Advantage‬‭is‬‭how‬‭well‬‭the‬‭simple‬‭machine‬‭is‬‭performing.‬‭How‬‭much‬‭easier‬‭it‬‭is‬‭making‬‭a‬ ‭job.‬‭IMA=‬‭Ideal‬‭Mechanical‬‭Advantage-‬‭In‬‭the‬‭PERFECT‬‭world‬‭(no‬‭friction)‬‭how‬‭much‬‭is‬‭the‬‭simple‬ ‭machine‬‭helping‬‭you‬‭do‬‭a‬‭job.‬‭AMA=‬‭Actual‬‭Mechanical‬‭Advantage.‬‭In‬‭this‬‭world,‬‭in‬‭the‬‭current‬ ‭state,‬‭how‬‭much‬‭is‬‭the‬‭simple‬‭machine‬‭helping‬‭you‬‭do‬‭a‬‭job‬‭(with‬‭friction).‬ ‭.‬ ‭Explain‬‭efficiency‬‭and‬‭list‬‭two‬‭ways‬‭to‬‭increase‬‭efficiency‬‭of‬‭a‬‭machine.‬ 5 ‭Efficiency‬‭is‬‭AMA‬‭as‬‭a‬‭percent‬‭of‬‭IMA.‬ ‭It‬‭states‬‭what‬‭percentage‬‭of‬‭your‬‭input‬‭effort‬‭goes‬‭to‬‭moving‬ ‭your‬‭load.‬ ‭For‬‭example,‬‭if‬‭efficiency‬‭is‬‭90%,‬‭that‬‭means‬‭90%‬‭of‬‭the‬‭input‬‭energy‬‭goes‬‭to‬‭moving‬‭the‬ ‭load.‬ ‭The‬‭other‬‭10%‬‭is‬‭“wasted”‬‭or‬‭used‬‭towards‬‭other‬‭things,‬‭such‬‭as‬‭overcoming‬‭friction‬‭or‬‭lifting‬ ‭the‬‭machine‬‭itself‬‭(ex‬‭the‬‭lever).‬ ‭To‬‭increase‬‭the‬‭efficiency‬‭of‬‭a‬‭machine:‬ ‭-‬ ‭Make‬‭the‬‭machine‬‭as‬‭light‬‭as‬‭possible‬‭(no‬‭excess‬‭weight‬‭to‬‭lift)‬ ‭-‬ ‭Minimize‬‭friction‬‭by‬‭ensuring‬‭all‬‭surfaces‬‭that‬‭make‬‭contact‬‭are‬‭smooth.‬ ‭.‬ E 6 ‭ xplain‬‭why‬‭a‬‭longer‬‭effort‬‭arm‬‭increases‬‭the‬‭mechanical‬‭advantage‬‭of‬‭a‬‭first‬‭class‬‭lever.‬ ‭-‬ ‭IMA‬‭=‬‭effort‬‭distance‬‭/‬‭load‬‭distance,‬‭therefore‬‭as‬‭the‬‭effort‬‭distance‬‭increases‬‭the‬‭value‬‭for‬ ‭IMA‬‭increases‬‭(assuming‬‭the‬‭load‬‭distance‬‭remains‬‭constant)‬ ‭-‬ ‭As‬‭the‬‭effort‬‭distance‬‭increases,‬‭less‬‭force‬‭is‬‭required‬‭to‬‭do‬‭the‬‭same‬‭work.‬‭Because‬‭W=Fd‬ ‭and‬‭work‬‭is‬‭equal‬‭on‬‭both‬‭sides‬‭of‬‭the‬‭lever‬‭(if‬‭it‬‭is‬‭100%‬‭efficient),‬‭there‬‭could‬‭be‬‭a‬‭large‬ ‭force‬‭on‬‭one‬‭side‬‭with‬‭a‬‭small‬‭distance,‬‭and‬‭a‬‭small‬‭force‬‭on‬‭the‬‭other‬‭side‬‭with‬‭a‬‭large‬ ‭distance.‬ ‭-‬ ‭Very‬‭technically,‬‭as‬‭a‬‭lever‬‭moves,‬‭both‬‭sides‬‭will‬‭move‬‭by‬‭the‬‭same‬‭angle.‬‭However,‬‭if‬‭the‬ ‭effort‬‭arm‬‭is‬‭longer‬‭than‬‭the‬‭load‬‭arm,‬‭the‬‭effort‬‭will‬‭travel‬‭a‬‭much‬‭greater‬‭distance‬‭than‬‭the‬ ‭load‬‭arm,‬‭meaning‬‭that‬‭a‬‭smaller‬‭force‬‭is‬‭required.‬ ‭7.‬ E‭ xplain‬‭why‬‭adding‬‭more‬‭pulleys‬‭increases‬‭the‬‭mechanical‬‭advantage‬‭of‬‭the‬‭system.‬‭What‬‭is‬ ‭the‬‭tradeoff?‬ ‭More‬‭pulleys‬‭means‬‭less‬‭force‬‭required‬‭to‬‭lift‬‭the‬‭load.‬‭This‬‭happens‬‭because‬‭there‬‭are‬‭a‬‭greater‬ ‭number‬‭of‬‭strings‬‭holding‬‭the‬‭object‬‭up,‬‭therefore‬‭a‬‭greater‬‭distance‬‭would‬‭need‬‭to‬‭be‬‭travelled‬‭by‬ ‭the‬‭effort‬‭in‬‭order‬‭to‬‭remove‬‭that‬‭amount‬‭of‬‭string‬‭and‬‭move‬‭the‬‭object.‬ ‭-‬ ‭The‬‭advantage‬‭is‬‭less‬‭force.‬‭The‬‭tradeoff‬‭is‬‭a‬‭longer‬‭effort‬‭distance.‬  ‭8.‬ ‭Describe‬‭the‬‭three‬‭classes‬‭of‬‭levers.‬‭Draw‬‭a‬‭diagram‬‭of‬‭each‬‭class‬‭and‬‭give‬‭an‬‭example.‬ ‭.‬ ‭What‬‭can‬‭be‬‭said‬‭about‬‭the‬‭mechanical‬‭advantage‬‭of‬‭all‬‭third‬‭class‬‭levers?‬‭Why?‬ 9 ‭Always‬‭less‬‭than‬‭1‬‭(but‬‭greater‬‭than‬‭0).‬‭This‬‭is‬‭because,‬‭by‬‭definition‬‭the‬‭effort‬‭arm‬‭is‬‭always‬‭shorter‬ ‭than‬‭the‬‭load‬‭arm.‬‭(A‬‭diagram‬‭in‬‭your‬‭answer‬‭might‬‭be‬‭helpful!)‬‭However,‬‭it’s‬‭okay‬‭that‬‭the‬ ‭mechanical‬‭advantage‬‭is‬‭less‬‭than‬‭1!‬‭We‬‭don’t‬‭want‬‭this‬‭lever‬‭to‬‭increase‬‭our‬‭force,‬‭we‬‭want‬‭it‬‭to‬ ‭increase‬‭the‬‭speed‬‭of‬‭the‬‭load!‬‭Think‬‭of‬‭a‬‭hockey‬‭stick.‬‭It’s‬‭a‬‭3rd‬‭class‬‭lever‬‭and‬‭it‬‭makes‬‭the‬‭puck‬ ‭travel‬‭much‬‭faster‬‭than‬‭how‬‭we‬‭are‬‭moving‬‭our‬‭hands.‬‭Another‬‭good‬‭example‬‭is‬‭throwing‬‭a‬‭ball‬‭with‬ ‭and‬‭without‬‭a‬‭ball‬‭launcher.‬ ‭10.‬‭How‬‭does‬‭the‬‭radius‬‭of‬‭a‬‭wheel‬‭change‬‭the‬‭MA‬‭of‬‭a‬‭wheel‬‭and‬‭axel?‬ ‭As‬‭the‬‭radius‬‭of‬‭a‬‭wheel‬‭increase,‬‭the‬‭distance‬‭the‬‭effort‬‭travels‬‭increases.‬‭Because‬‭a‬‭greater‬ ‭distance‬‭is‬‭travelled,‬‭a‬‭smaller‬‭force‬‭is‬‭required‬‭to‬‭produce‬‭the‬‭same‬‭amount‬‭of‬‭work.‬‭This‬‭is‬ ‭assuming‬‭the‬‭effort‬‭force‬‭is‬‭on‬‭the‬‭wheel‬‭and‬‭the‬‭load‬‭is‬‭on‬‭the‬‭axle.‬ ‭If‬‭this‬‭is‬‭reversed‬‭(as‬‭in‬‭the‬ ‭mousetrap‬‭cars),‬‭then‬‭the‬‭opposite‬‭is‬‭true.‬ ‭ nother‬‭way‬‭to‬‭think‬‭about‬‭it…‬‭A‬‭wheel‬‭is‬‭basically‬‭a‬‭lever‬‭that‬‭turns‬‭360‬‭degrees!‬‭Compare‬‭a‬‭round‬ A ‭doorknob‬‭to‬‭a‬‭straight‬‭handle‬‭doorknob.‬‭The‬‭longer‬‭the‬‭lever‬‭arm,‬‭the‬‭more‬‭MA,‬‭so‬‭same‬‭with‬‭the‬ ‭wheel.‬‭The‬‭radius‬‭is‬‭the‬‭equivalent‬‭of‬‭the‬‭lever‬‭arm,‬‭except‬‭it’s‬‭360‬‭degrees‬‭around.‬ ‭11.‬ H ‭ ow‬‭does‬‭an‬‭inclined‬‭plane‬‭make‬‭it‬‭easier‬‭to‬‭lift‬‭a‬‭heavy‬‭object?‬‭Why‬‭do‬‭flatter‬‭inclined‬ ‭planes‬‭lead‬‭to‬‭an‬‭even‬‭smaller‬‭force‬‭required?‬ ‭An‬‭inclined‬‭plane‬‭makes‬‭it‬‭easier‬‭to‬‭lift‬‭a‬‭heavy‬‭load‬‭because‬‭a‬‭ramp‬‭causes‬‭the‬‭force‬‭to‬‭cover‬‭more‬ ‭distance,‬‭which‬‭means‬‭less‬‭force‬‭(compared‬‭to‬‭just‬‭listing‬‭it).‬‭When‬‭an‬‭inclined‬‭plane‬‭is‬‭less‬‭steep,‬ ‭less‬‭force‬‭is‬‭required‬‭to‬‭move‬‭the‬‭object‬‭because‬‭the‬ ‭ramp‬‭is‬‭doing‬‭lots‬‭of‬‭the‬‭lifting‬‭for‬‭us.‬‭The‬‭ramp‬ ‭pushes‬‭up‬‭on‬‭the‬‭box‬‭so‬‭we‬‭don’t‬‭have‬‭to‬‭as‬‭much.‬ ‭ ‬‭less‬‭steep‬‭ramp‬‭is‬‭much,‬‭much‬‭longer,‬‭so‬‭we‬‭push‬ A ‭with‬‭less‬‭force,‬‭but‬‭much‬‭more‬‭distance.‬ ‭Calculation‬‭Questions‬ ‭If‬‭you‬‭found‬‭any‬‭questions‬‭tricky,‬‭see‬‭if‬‭one‬‭of‬‭these‬‭formulas‬‭can‬‭help‬‭before‬‭you‬‭check‬‭the‬‭answers‬ ‭F‬‭=‬‭m‬‭x‬‭a‬ ‭W‬‭=‬‭F‬‭x‬‭d‬ ‭Force‬ ‭=‬ ‭mass‬ ‭x‬ ‭acceleration‬ ‭(‬‭work‬ ‭=‬ ‭force‬ ‭x‬ ‭displacement)‬ ‭(Newtons)‬ ‭(kilograms)‬‭(meters/second/second)‬ ‭(Joules)‬ ‭(Newtons)‬ ‭(meters)‬ ‭Weight‬‭=‬‭force‬‭due‬‭to‬‭gravity‬‭(Newtons)‬ ‭if‬‭there‬‭is‬‭no‬‭displacement,‬‭there‬‭is‬‭no‬‭work‬ ‭a‬‭g‬‭=‬‭10m/s‬‭2‬‭(acceleration‬‭due‬‭to‬‭gravity)‬ ‭But‬‭usually‬‭displacement‬‭=‬‭distance‬ ‭𝑒𝑓𝑓𝑜𝑟𝑡‬‭‬‭𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒‬ ‭𝑙𝑜𝑎𝑑‬‭‭𝑓 ‬ 𝑜𝑟𝑐𝑒‬ ‭ 𝑀𝐴‬ 𝐴 ‭IMA‬‭=‬ ‭𝑙𝑜𝑎𝑑‬‭‭𝑑 ‬ 𝑖𝑠𝑡𝑎𝑛𝑐𝑒‬ ‭AMA‬‭=‬ ‭𝑒𝑓𝑓𝑜𝑟𝑡‬‭‬‭𝑓𝑜𝑟𝑐𝑒‬ ‭Efficiency‬‭=‬ ‭𝐼𝑀𝐴‬ × ‭100%‬ ‭1.‬ ‭Calculating‬‭the‬‭work‬‭done‬‭in‬‭the‬‭following‬‭instances:‬ ‭a.‬ ‭Pushing‬‭a‬‭car‬‭15‬‭m‬‭using‬‭a‬‭pushing‬‭force‬‭of‬‭500N‬‭(assume‬‭the‬‭force‬‭of‬‭friction‬‭is‬ ‭negligible)‬ ‭W‬‭=‬‭Fd‬‭=‬‭500N‬‭*‬‭15m‬‭=‬‭7500J‬ ‭b.‬ ‭Lifting‬‭a‬‭100N‬‭sewing‬‭machine‬‭from‬‭the‬‭floor‬‭to‬‭a‬‭tabletop‬‭75‬‭cm‬‭high.‬ ‭Convert:‬‭75cm‬‭=‬‭0.75m‬ ‭W‬‭=‬‭Fd‬‭=‬‭100N‬‭*‬‭0.75m‬‭=‬‭75J‬ ‭c.‬ ‭Lifting‬‭a‬‭10kg‬‭weight‬ ‭1m‬‭off‬‭the‬‭ground‬‭and‬‭then‬‭putting‬‭it‬‭back‬‭down.‬ ‭W‬‭=‬‭Fd‬‭but‬‭since‬‭the‬‭weight‬‭ends‬‭up‬‭where‬‭it‬‭started‬‭(back‬‭on‬‭the‬‭ground)‬‭there‬‭is‬‭no‬‭work‬‭done.‬ ‭.‬‭How‬‭much‬‭force‬‭is‬‭used‬‭if‬‭a‬‭car‬‭is‬‭pushed‬‭25‬‭m‬‭and‬‭60‬‭kJ‬‭of‬‭work‬‭is‬‭done.‬ 2 ‭Convert:‬‭60kJ‬‭=‬‭60‬‭000‬‭J‬ ‭W‬‭=‬‭Fd‬ ‭60000J‬‭=‬‭F‬‭*‬‭25m‬ ‭F‬‭=‬‭2400‬‭N‬ ‭.‬‭Calculate‬‭the‬‭distance‬‭moved‬‭if‬‭2‬‭kJ‬‭of‬‭work‬‭is‬‭done‬‭and‬‭a‬‭force‬‭of‬‭500N‬‭is‬‭put‬‭forth‬‭to‬‭move‬‭a‬ 3 ‭rock.‬ ‭W‬‭=‬‭Fd‬ ‭2000‬‭=‬‭500N‬‭*‬‭d‬ ‭d‬‭=‬‭4m‬ ‭.‬‭A‬‭tow‬‭truck‬‭is‬‭towing‬‭a‬‭980‬‭kg‬‭car.‬ ‭The‬‭car‬‭is‬‭steadily‬‭gaining‬‭speed‬‭with‬‭an‬‭acceleration‬‭of‬ ‭0.8‬ 4 ‭m/s‬‭2‭.‬ ‬ ‭a.‬ ‭Find‬‭the‬‭force‬‭exerted‬‭by‬‭the‬‭tow‬‭truck.‬ ‭F‬‭=‬‭ma‬ ‭F‬‭=‬‭980‬‭*‬‭0.8‬ ‭F‬‭=‬‭784N‬  ‭.‬ ‭Using‬‭this‬‭force,‬‭find‬‭the‬‭work‬‭done‬‭by‬‭the‬‭truck‬‭to‬‭move‬‭the‬‭car‬‭a‬‭distance‬‭of‬‭30‬‭m.‬ b ‭W‬‭=‬‭Fd‬‭=‬‭784‬‭N‬‭*‬‭30m‬‭=‬‭23520‬‭J‬ ‭.‬‭Calculate‬‭the‬‭force‬‭of‬‭gravity‬‭acting‬‭on‬‭a‬‭penny‬‭dropped‬‭from‬‭the‬‭top‬‭of‬‭the‬‭CN‬‭tower‬‭given‬‭that‬‭a‬ 5 ‭penny‬‭weighs‬‭2.3‬‭g.‬ ‭2.3g‬‭=‬‭0.0023kg‬ ‭F‬‭=‬‭mg‬‭=‬‭0.0023‬‭kg‬‭*‬‭10m/s‬‭2‬‭=‬‭0.023N‬ ‭.‬‭If‬‭an‬‭output‬‭force‬‭is‬‭5‬‭times‬‭larger‬‭than‬‭the‬‭input‬‭force,‬‭what‬‭is‬‭the‬‭mechanical‬‭advantage?‬ 6 ‭AMA‬‭=‬‭output‬‭force/input‬‭force‬‭=‬‭5‬ ‭This‬‭means‬‭than‬‭the‬‭machine‬‭can‬‭multiply‬‭the‬‭effort‬‭force‬‭by‬‭5!‬ ‭.‬‭If‬‭0.6N‬‭of‬‭force‬‭is‬‭required‬‭to‬‭lift‬‭a‬‭rock‬‭of‬‭36N,‬‭what‬‭is‬‭the‬‭mechanical‬‭advantage?‬ 7 ‭AMA‬‭=‬‭load‬‭force/effort‬‭force‬‭=‬‭36N‬‭/‬‭0.6N‬‭=‬‭60‬‭(wow!)‬ ‭8.‬‭Using‬‭a‬‭crowbar,‬‭you‬‭are‬‭able‬‭to‬‭apply‬‭a‬‭force‬‭of‬‭25N‬‭to‬‭lift‬‭a‬‭stone‬‭with‬‭a‬‭load‬‭force‬‭of‬‭250N.‬ ‭a.‬ ‭What‬‭is‬‭the‬‭mechanical‬‭advantage‬‭of‬‭this‬‭lever?‬ ‭AMA‬‭=‬‭load‬‭force/effort‬‭force‬‭=‬‭250N‬‭/‬‭25N‬‭=‬‭10‬ ‭b.‬ ‭What‬‭type‬‭of‬‭lever‬‭is‬‭this?‬ ‭Crowbars‬‭are‬‭always‬‭1st‬‭class‬‭levers!‬ ‭.‬‭A‬‭pulley‬‭system‬‭is‬‭used‬‭to‬‭raise‬‭a‬‭load.‬ ‭The‬‭input‬‭force‬‭of‬‭the‬‭pulley‬‭system‬‭is‬‭4N.‬ ‭The‬‭output‬ 9 ‭force‬‭is‬‭12N.‬ ‭What‬‭is‬‭the‬‭mechanical‬‭advantage‬‭of‬‭this‬‭system?‬‭Did‬‭you‬‭calculate‬‭the‬‭AMA‬‭or‬‭IMA?‬ ‭This‬‭is‬‭AMA‬‭because‬‭we‬‭are‬‭using‬‭measured‬‭forces.‬ ‭AMA‬‭=‬‭load‬‭force/effort‬‭force‬‭=‬‭12N‬‭/‬‭4N‬‭=‬‭3‬ ‭Data‬‭Analysis‬‭Questions‬ ‭1.‬ ‭Calculate‬‭the‬‭load‬‭force.‬ ‭The‬‭load‬‭is‬‭a‬‭1kg‬‭mass.‬ ‭1kg‬‭=‬‭10N.‬ ‭Load‬‭Force‬‭=‬‭10N‬ ‭2.‬ ‭Calculate‬‭the‬‭work‬‭required‬‭to‬‭lift‬‭the‬‭load.‬ ‭W=Fd.‬ ‭F=10N‬ ‭d=0.5m‬ ‭→‬‭W=10*0.5‬‭→‬‭W=5J‬ ‭3.‬ ‭Describe‬‭the‬‭relationship‬‭between‬‭#‬‭of‬‭pulleys‬‭and‬‭effort‬‭force.‬ ‭As‬‭the‬‭number‬‭of‬‭pulleys‬‭increases‬‭(from‬‭1‬‭to‬‭4),‬‭the‬‭effort‬‭force‬‭required‬‭to‬‭lift‬‭a‬‭10N‬‭load‬‭decreases.‬ ‭.‬ ‭Describe‬‭the‬‭relationship‬‭between‬‭#‬‭of‬‭pulleys‬‭and‬‭effort‬‭distance.‬ 4 ‭As‬‭the‬‭number‬‭of‬‭pulleys‬‭increases‬‭(from‬‭1‬‭to‬‭4),‬‭the‬‭effort‬‭distance‬‭required‬‭to‬‭lift‬‭a‬‭load‬‭to‬‭a‬‭50cm‬ ‭height‬‭increases.‬  ‭5.‬ C ‭ omplete‬‭the‬‭following‬‭table‬‭by‬‭calculating‬‭missing‬‭values‬‭for‬‭the‬‭IMA,‬‭AMA,‬‭work‬ ‭in‬‭and‬ ‭efficiency‬ ‭ able‬‭2‬ T ‭Note:‬‭Load‬‭Force‬‭=‬‭10N;‬‭Load‬‭Distance‬‭=‬‭0.5m‬ ‭If‬‭the‬‭machine‬‭were‬‭100%‬‭efficient,‬‭the‬‭work‬‭would‬‭equal‬‭5J‬‭(W‬‭L‬‭=‬‭F‭L‬ ‭* ‬ d‬‭L‭)‬ ‬ ‭ umber‬‭of‬ N ‭IMA‬‭=‬ ‭𝑒𝑓𝑓𝑜𝑟𝑡‬‭‬‭𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒‬ ‭𝑙𝑜𝑎𝑑‬‭‭𝑓 ‬ 𝑜𝑟𝑐𝑒‬ ‭AMA‬‭=‬ ‭𝑒𝑓𝑓𝑜𝑟𝑡‬‭‬‭𝑓𝑜𝑟𝑐𝑒‬ ‭ ork‬‭In‬‭(J)‬ W ‭Efficiency‬‭=‬ ‭𝑙𝑜𝑎𝑑‬‭‭𝑑 ‬ 𝑖𝑠𝑡𝑎𝑛𝑐𝑒‬ ‭Pulleys‬ ‭W‭E‬ ‬ ‭=‬‭F‭E‬ ‬‭*d‬‭E‬ ‭𝐴𝑀𝐴‬ × ‭100%‬ ‭𝐼𝑀𝐴‬ ‭1‬ ‭1‬ ‭0.952‬ ‭5.25‬ ‭95.2%‬ ‭2‬ ‭2‬ ‭1.75‬ ‭5.‬ ‭7‬ × ‭0.‬ ‭96‬ = ‭5.‬ ‭47‬ ‭87.5%‬ ‭3‬ ‭3‬ ‭10‬ = ‭2.‬ ‭63‬ ‭5.62‬ ‭2‬.‭63‬ = ‭87‬. ‭7%‬ ‭ ‬.‭8‬ 3 ‭3‬ ‭4‬ ‭4‬ ‭10‬ = ‭3.‬ ‭22‬ ‭3.‬ ‭1‬ × ‭2.‬ ‭01‬ = ‭6.‬ ‭23‬ ‭3‬.‭22‬ = ‭80‬. ‭5%‬ ‭ ‬.‭1‬ 3 ‭4‬ ‭6.‬ C ‭ alculate‬‭the‬‭efficiency‬‭for‬‭the‬‭3-pulley‬‭system‬‭in‬‭two‬‭different‬‭ways.‬‭Are‬‭they‬‭the‬‭same?‬ ‭Explain‬‭why‬‭or‬‭why‬‭not.‬ ‭ 𝑀𝐴‬ 𝐴 ‭𝑊‬ ‭Efficiency‬‭=‬ ‭𝐼𝑀𝐴‬ × ‭100%‬ ‭Efficiency‬‭=‬‭𝑊‬‭𝐿‬ × ‭100%‬ ‭ MA‬‭=‬‭2.63‬ ‭IMA‬‭=3‬ A ‭𝐸‬ ‭2‬.‭63‬ ‭ ‭L‬ ‬‭=‬‭work‬‭required‬‭to‬‭lift‬‭load‬‭(w/o‬‭pulley)‬ W ‭Efficiency‬‭=‬ ‭3‬ = ‭87‬. ‭7%‬ ‭𝑊‬‭𝐿‬ = ‭10‬ × ‭0.‬ ‭5‬ = ‭5‭𝐽‬ ‬ ‭ ‭E‬ ‬‭=‬‭work‬‭actually‬‭done‬‭when‬‭using‬‭3‬‭pulleys‬ W ‭𝑊‬‭𝐸‬ = ‭3.‬ ‭8‬ × ‭1.‬ ‭48‬ = ‭5.‬ ‭62‬‭𝐽‬ ‭5‬ ‭Efficiency‬‭=‬ ‭5‬.‭62‬ = ‭87‬. ‭7%‬ ‭ s‬‭long‬‭as‬‭all‬‭calculated‬‭values‬‭aren’t‬‭rounded‬‭mid-question,‬‭the‬‭efficiency‬‭is‬‭the‬‭same‬‭when‬ A ‭calculated‬‭both‬‭ways.‬ ‭This‬‭is‬‭true‬‭because‬‭both‬‭calculations‬‭used‬‭the‬‭same‬‭measured‬‭values‬‭(load‬ ‭force,‬‭load‬‭distance,‬‭effort‬‭force‬‭and‬‭effort‬‭distance)‬‭in‬‭the‬‭calculations.‬ ‭7.‬ T ‭ he‬‭graph‬‭in‬‭Figure‬‭3‬‭shows‬‭that‬‭the‬‭efficiency‬‭decreases‬‭as‬‭more‬‭pulleys‬‭are‬‭added.‬‭Explain‬ ‭why‬‭this‬‭trend‬‭occurs.‬ ‭As‬‭you‬‭add‬‭more‬‭pulleys,‬‭you‬‭are‬‭adding‬‭more‬‭area‬‭for‬‭the‬‭rope‬‭to‬‭rub‬‭up‬‭against‬‭the‬‭pulleys,‬ ‭therefore‬‭more‬‭friction‬‭is‬‭being‬‭added‬‭to‬‭the‬‭system.‬ ‭The‬‭pulleys‬‭still‬‭make‬‭the‬‭job‬‭easier,‬‭but‬ ‭more‬‭friction‬‭is‬‭added‬‭into‬‭the‬‭system,‬‭and‬‭therefore‬‭it‬‭becomes‬‭less‬‭efficient.‬‭There‬‭is‬‭also‬ ‭an‬‭additional‬‭force‬‭needed‬‭to‬‭lift‬‭the‬‭pulley‬‭system‬‭itself.‬ ‭More‬‭pulleys‬‭means‬‭more‬‭extra‬ ‭mass‬‭to‬‭lift.‬ ‭8.‬ I‭MA‬‭and‬‭AMA‬‭have‬‭no‬‭units.‬ ‭Explain‬‭why.‬ ‭Mechanical‬‭advantage‬‭is‬‭a‬‭RATIO.‬ ‭When‬‭comparing‬‭(dividing)‬‭two‬‭quantities‬‭with‬‭the‬‭same‬ ‭units,‬‭the‬‭units‬‭can‬‭“cancel”.‬ ‭MA‬‭tell‬‭us‬‭how‬‭many‬‭times‬‭“easier”‬‭the‬‭machine‬‭makes‬‭the‬‭job.‬ ‭Side‬‭note:‬‭this‬‭is‬‭different‬‭from‬‭density,‬‭which‬‭is‬‭a‬‭RATE‬‭and‬‭needs‬‭units‬‭(g/mL)‬ ‭Scientific‬‭Method‬‭Review‬ ‭REVIEW‬‭QUESTIONS-‬‭Knowledge‬‭and‬‭Understanding‬ ‭1.‬ ‭What‬‭is‬‭a‬‭similarity‬‭and‬ ‭difference‬‭between‬‭mass‬‭and‬ ‭weight?‬ ‭a.‬ ‭Differences-‬‭Mass‬‭is‬‭the‬ ‭amount‬‭of‬‭matter‬‭in‬‭an‬ ‭object‬‭(grams‬‭or‬‭kg)‬‭and‬ ‭weight‬‭is‬‭a‬‭force‬‭(N)‬‭that‬ ‭depends‬‭on‬‭the‬‭amount‬‭of‬ ‭gravitational‬‭pull.‬ ‭b.‬ ‭Similarities-‬‭as‬‭mass‬ ‭increases,‬‭so‬‭would‬ ‭weight.‬‭Therefore,‬‭there‬‭is‬ ‭a‬‭direct‬‭relationship‬ ‭between‬‭these‬‭two‬‭terms.‬ ‭2.‬ H ‭ ow‬‭does‬‭temperature‬‭affect‬ ‭density?‬‭When‬‭an‬‭object‬‭gains‬‭energy?‬‭When‬‭an‬‭object‬‭loses‬‭energy?‬ ‭In‬‭general:‬‭Increase‬‭temperature,‬‭decreases‬‭density‬‭and‬‭Decreased‬‭Temperature,‬‭increases‬‭density‬ ‭When‬‭an‬‭object‬‭gains‬‭energy,‬‭the‬‭particles‬‭move‬‭faster‬‭and‬‭further‬‭apart-‬‭decreasing‬‭density‬ ‭When‬‭an‬‭object‬‭loses‬‭energy,‬‭the‬‭particles‬‭more‬‭slower‬‭and‬‭closer‬‭together-‬‭increasing‬‭density‬ ‭3.‬ C ‭ ompare‬‭the‬‭density‬‭between-‬‭solid,‬‭liquid‬‭and‬‭gas.‬‭Use‬‭words‬‭and‬‭drawings‬‭to‬‭explain‬‭the‬ ‭differences.‬ ‭ olids‬‭are‬‭typically‬‭MORE‬‭dense,‬‭as‬‭the‬‭particles‬‭are‬‭close‬‭together‬‭with‬‭only‬‭a‬‭small‬‭amount‬‭of‬ S ‭space‬‭between‬‭them‬ ‭Liquids‬‭are‬‭typically‬‭LESS‬‭dense‬‭than‬‭solids,‬‭the‬‭particles‬‭are‬‭further‬‭apart,‬‭and‬‭actually‬‭move‬ ‭around‬‭each‬‭other‬‭allowing‬‭for‬‭flow‬ ‭Gases‬‭are‬‭LESS‬‭dense‬‭than‬‭solids‬‭and‬‭liquids,‬‭the‬‭particles‬‭are‬‭moving‬‭quickly‬‭and‬‭far‬‭apart.‬ ‭4.‬ E ‭ xplain‬‭what‬‭it‬‭means‬‭to‬‭be‬‭‘more‬‭dense’.‬‭Use‬‭a‬‭specific‬‭example,‬‭and‬‭include‬‭a‬‭diagram‬‭of‬ ‭the‬‭particles.‬ ‭To‬‭be‬‭more‬‭dense,‬‭means‬‭that‬‭you‬‭have‬‭more‬‭particles‬‭in‬‭a‬‭given‬‭space.‬ I‭f‬‭you‬‭see‬‭the‬‭image‬‭below.‬‭Both‬‭boxes‬‭are‬‭the‬‭same‬‭amount‬‭of‬‭space‬‭(volume),‬‭but‬‭the‬‭one‬‭on‬‭the‬ ‭left‬‭has‬‭more‬‭particles‬‭in‬‭the‬‭same‬‭space.‬‭Therefore,‬‭we‬‭say‬‭it‬‭is‬‭more‬‭dense‬ ‭5.‬ D ‭ efine‬‭the‬‭following‬‭terms.‬‭Include‬‭the‬‭units‬‭of‬‭measurement‬‭for‬‭each.‬ ‭a-‬‭Mass-‬‭Amount‬‭of‬‭matter‬‭in‬‭a‬‭given‬‭object-‬‭measured‬‭in‬‭grams‬ ‭b-Volume-‬‭Amount‬‭of‬‭space‬‭an‬‭object‬‭takes‬‭up-‬‭mL‬‭or‬‭cm‬‭3‬ ‭c-‬‭Matter-‬‭anything‬‭that‬‭has‬‭mass‬‭or‬‭takes‬‭up‬‭space.‬‭Anything‬‭made‬‭from‬‭particles‬‭on‬‭the‬ ‭ eriodic‬‭table‬ p ‭.‬ ‭If‬‭you‬‭have‬‭23456‬‭grams,‬‭how‬‭many‬‭kgs‬‭do‬‭you‬‭have?‬‭Show‬‭your‬‭approach‬ 6 ‭23456‬‭grams‬‭=‬‭23.456‬‭kg‬ ‭You‬‭move‬‭the‬‭decimal‬‭place‬‭3‬‭times‬‭to‬‭the‬‭left‬‭OR‬‭divide‬‭by‬‭1000‬ ‭.‬ ‭What‬‭is‬‭displacement?‬ ‭How‬‭can‬‭it‬‭help‬‭you‬‭calculate‬‭volume?‬‭Explain‬‭the‬‭steps?‬ 7 ‭Displacement-‬‭by‬‭submerging‬‭an‬‭object‬‭in‬‭water,‬‭and‬‭determining‬‭how‬‭much‬‭the‬‭water‬‭moves,‬ ‭allows‬‭you‬‭to‬‭calculate‬‭the‬‭volume‬‭of‬‭the‬‭object.‬ ‭.‬ ‭Explain‬‭the‬‭steps‬‭you‬‭would‬‭take‬‭to‬‭determine‬‭if‬‭an‬‭object‬‭would‬‭float‬‭or‬‭sink‬‭in‬‭water.‬ 8 ‭Option‬‭1-‬‭Calculated‬‭Density‬ ‭1.‬ ‭Find‬‭mass‬‭using‬‭the‬‭balance‬ ‭2.‬ ‭Find‬‭the‬‭volume‬‭using‬‭displacement‬‭or‬‭LxWxH‬ ‭3.‬ ‭Using‬‭Mass/‬‭Volume-‬‭calculate‬‭Density‬ ‭Option‬‭2-‬‭Put‬‭in‬‭water-‬‭does‬‭it‬‭float?‬‭Does‬‭it‬‭sink?‬ ‭Application‬‭Questions‬ ‭1.‬‭Calculate‬ ‭a)‬ ‭The‬‭mean‬‭from-‬‭14,‬‭16,‬‭17,‬‭86,‬‭47,‬‭59,‬‭36,‬‭49,‬‭65,‬‭19-‬‭40.8‬ ‭b)‬ ‭The‬‭Median‬‭from-‬‭15,‬‭16,‬‭12,‬‭34,‬‭24,‬‭12,‬‭23,‬‭24,‬‭12,‬‭12,‬‭24,‬‭32,‬‭13-‬‭16‬ ‭c)‬ ‭The‬‭Median‬‭from-‬‭15,‬‭16,‬‭12,‬‭34,‬‭24,‬‭12,‬‭23,‬‭24,‬‭12,‬‭12,‬‭24,‬‭32,‬‭13,‬‭17-‬‭16.‬‭5‬ ‭d)‬ ‭The‬‭Mode‬‭from-‬‭15,‬‭16,‬‭12,‬‭34,‬‭24,‬‭12,‬‭12,‬‭24,‬‭12,‬‭12,‬‭24,‬‭32,‬‭12-‬‭12‬ ‭2.‬‭State‬‭the‬‭type‬‭of‬‭data‬‭of‬‭each‬‭example‬‭below‬ ‭A-‬‭Blood‬‭Pressure‬‭-‬‭Continuous‬ ‭B-‬‭Number‬‭of‬‭Asthma‬‭Attacks‬‭per‬‭Week‬‭-‬‭Discrete‬ ‭C-‬ ‭Your‬‭ranking‬‭of‬‭of‬‭romantic‬‭comedies‬‭-‬‭Ordinal‬ ‭D-‬‭Blood‬‭Types‬‭of‬‭A,‬‭B,‬‭O‬‭-‬‭Categorical‬ ‭E-‬‭Number‬‭of‬‭Children‬‭a‬‭Family‬‭has-‬‭Discrete‬ ‭3.‬‭The‬‭density‬‭of‬‭silver‬‭(Ag)‬‭is‬‭10.5‬‭g/cm‬‭3‭.‬ ‬ ‭Find‬‭the‬‭mass‬‭of‬‭Ag‬‭that‬‭occupies‬‭965‬‭cm‬‭3‬ ‭of‬‭space.‬ ‭4.‬‭A‬‭2.75‬‭kg‬‭sample‬‭of‬‭a‬‭substance‬‭occupies‬‭a‬‭volume‬‭of‬‭250.0‬‭cm‬‭3‭.‬ ‬ ‭Find‬‭its‬‭density‬‭in‬‭g/cm‬‭3‭.‬ ‬ ‭.‬‭Under‬‭certain‬‭conditions,‬‭oxygen‬‭gas‬‭(O‬‭2‭)‬ ‬‭has‬‭a‬‭density‬‭of‬‭0.00134‬‭g/mL.‬ ‭Find‬‭the‬‭volume‬ 5 ‭occupied‬‭by‬‭250.0‬‭g‬‭of‬‭O‬‭2‬ ‭under‬‭the‬‭same‬‭conditions.‬ ‭.‬‭Find‬‭the‬‭volume‬‭that‬‭35.2‬‭g‬‭of‬‭carbon‬‭tetrachloride‬‭(CCl‬‭4‭)‬ ‬‭will‬‭occupy‬‭if‬‭it‬‭has‬‭a‬‭density‬‭of‬‭1.60‬ 6 ‭g/mL.‬ ‭.‬‭The‬‭density‬‭of‬‭ethanol‬‭is‬‭0.789‬‭g/mL.‬ ‭Find‬‭the‬‭mass‬‭of‬‭a‬‭sample‬‭of‬‭ethanol‬‭that‬‭has‬‭a‬‭volume‬‭of‬ 7 ‭150.0‬‭mL.‬ ‭.‬‭A‬‭Rock‬‭with‬‭a‬‭mass‬‭of‬‭73.65‬‭grams‬‭is‬‭placed‬‭in‬‭a‬‭graduated‬‭cylinder‬‭(image‬‭below).‬‭Calculate‬‭the‬ 8 ‭density‬‭of‬‭the‬‭rock.‬ ‭.‬‭Ameet‬‭decided‬‭to‬‭determine‬‭the‬‭volume‬‭of‬‭this‬‭rubber‬‭duck‬‭using‬‭the‬‭displacement‬‭method,‬‭as‬ 9 ‭seen‬‭in‬‭the‬‭images‬‭below.‬ ‭Explain‬‭the‬‭error‬‭in‬‭his‬‭method.‬ ‭ he‬‭rubber‬‭ducky‬‭is‬‭not‬‭fully‬‭submerged‬‭in‬‭water.‬‭Therefore,‬‭if‬‭you‬‭are‬‭trying‬‭to‬‭calculate‬‭volume‬‭of‬ T ‭the‬‭rubber‬‭duck,‬‭you‬‭will‬‭not‬‭get‬‭the‬‭correct‬‭volume‬‭(too‬‭low!),‬‭unless‬‭the‬‭entire‬‭duck‬‭is‬‭under‬‭water.‬ ‭10.‬‭Calculate‬‭the‬‭density‬‭of‬‭the‬‭objects‬‭below‬ 1‭ 1.‬‭Using‬‭the‬‭table‬‭below,‬‭make‬‭a‬‭density,‬‭make‬‭a‬‭density‬‭column‬‭of‬‭the‬‭following‬‭items-‬ ‭Iron‬‭(Cast),‬ ‭Iron‬‭(Wrought),‬‭Aluminum,‬‭Feldspar,‬‭Ice,‬‭Ivory,‬‭Paraffin‬‭and‬‭Wood‬‭(Maple).‬ ‭a)‬ ‭ )‬‭Using‬‭the‬‭table‬‭above‬‭identify‬‭the‬‭unknown‬‭substance.‬‭The‬‭unknown‬‭substance‬‭has‬‭a‬‭mass‬‭20.64‬ b ‭g‬‭and‬‭takes‬‭up‬‭86cm‬‭3‬ ‭of‬‭space.‬‭What‬‭is‬‭the‬‭substance?‬ c‭ )‬‭Using‬‭the‬‭table‬‭above‬‭identify‬‭the‬‭unknown‬‭substance.‬‭The‬‭unknown‬‭substance‬‭has‬‭a‬‭mass‬‭68.4‬‭g‬ ‭and‬‭takes‬‭up‬‭45‬‭cm‬‭3‬ ‭of‬‭space.‬‭What‬‭is‬‭the‬‭substance?‬ 1‭ 2.‬‭For‬‭each‬‭scatter‬‭plot,‬ ‭a)‬‭State‬‭whether‬‭the‬‭data‬‭has‬‭a‬‭linear‬‭relationship,‬‭a‬‭non-linear‬‭relationship,‬‭or‬‭neither.‬ ‭b)‬‭If‬‭the‬‭data‬‭is‬‭related,‬‭describe‬‭the‬‭relationship.‬‭Is‬‭it‬‭positive‬‭or‬‭negative?‬‭Is‬‭it‬‭strong‬‭or‬‭weak?‬ ‭Explain‬‭your‬‭choices.‬ ‭.‬ L‭ inear‬ a ‭.‬ N a ‭ on-linear‬ ‭a.‬ ‭No‬‭correlation‬ ‭b.‬ ‭Positive,‬‭moderate‬ ‭b.‬ ‭Positive,‬ ‭moderate/strong‬ ‭13.‬‭Compare‬‭these‬‭two‬‭graphs.‬‭Which‬‭shows‬‭a‬‭stronger‬‭linear‬‭correlation,‬‭and‬‭why?‬ ‭Graph‬‭B‬‭has‬‭a‬‭stronger‬‭linear‬‭correlation,‬‭because‬‭almost‬‭all‬‭points‬‭would‬‭be‬‭on‬‭a‬‭LoBF.‬ 1‭ 4.‬‭Audrey‬‭recorded‬‭the‬‭temperature‬‭from‬‭their‬‭apartment‬‭balcony‬‭every‬‭day‬‭at‬‭the‬‭same‬‭time‬‭for‬ ‭the‬‭first‬‭10‬‭days‬‭in‬‭March,‬‭missing‬‭Day‬‭6.‬ ‭.‬ C a ‭ reate‬‭a‬‭scatter‬‭plot‬‭of‬‭the‬‭data.‬ ‭b.‬ ‭Given‬‭that‬‭the‬‭r‬‭2‬ ‭value‬‭is‬‭approximately‬‭0.888,‬‭describe‬‭the‬‭relationship‬‭shown‬‭on‬‭the‬‭scatter‬ ‭plot‬‭as:‬ ‭i.‬ ‭linear‬‭or‬‭non-linear‬  i‭i.‬ ‭positive‬‭or‬‭negative,‬‭and‬ ‭iii.‬ ‭strong,‬‭moderate,‬‭or‬‭weak.‬ c‭.‬ ‭Create‬‭a‬‭line‬‭of‬‭best‬‭fit‬‭on‬‭your‬‭graph.‬ ‭d.‬ ‭Estimate‬‭the‬‭temperature‬‭on‬‭Day‬‭6,‬‭to‬‭the‬‭nearest‬‭degree.‬ ‭e.‬ ‭Use‬‭the‬‭line‬‭of‬‭best‬‭fit‬‭to‬‭predict‬‭when‬‭the‬‭temperature‬‭will‬‭reach‬‭6‬‭°C.‬ ‭f.‬ ‭What‬‭assumptions‬‭did‬‭you‬‭make‬‭when‬‭using‬‭this‬‭data‬‭to‬‭estimate‬‭or‬‭predict‬‭values‬‭between‬ ‭or‬‭beyond‬‭known‬‭values?‬ ‭a.‬ ‭b.‬‭Linear,‬‭strong‬‭positive‬‭correlation‬ ‭c.‬‭(Drawn‬‭on‬‭graph)‬ ‭.‬‭The‬‭line‬‭seems‬‭to‬‭have‬‭a‬‭point‬‭(6,‬‭–2)‬‭so‬‭we‬ d ‭can‬‭interpolate‬‭the‬‭temperature‬‭on‬‭Day‬‭6‬‭to‬ ‭be‬‭–2‬‭o‬‭C.‬‭Since‬‭it‬‭is‬‭a‬‭strong‬‭correlation,‬‭this‬‭is‬ ‭probably‬‭accurate.‬ ‭.‬‭The‬‭line‬‭seems‬‭to‬‭have‬‭a‬‭point‬‭(12.5,‬‭6)‬‭so‬ e ‭we‬‭can‬‭extrapolate‬‭that‬‭the‬‭temperature‬‭will‬ ‭reach‬‭6‬‭o‬‭C‬‭on‬‭Day‬‭12.‬‭Since‬‭this‬‭is‬‭outside‬‭the‬ ‭bounds‬‭of‬‭our‬‭data,‬‭this‬‭is‬‭not‬‭reliable.‬ f‭.‬‭We‬‭assumed‬‭that‬‭the‬‭LoBF‬‭represents‬‭the‬‭temperature‬‭each‬‭day‬‭quite‬‭strongly,‬‭because‬‭the‬‭r‭2‬ ‬ ‭was‬ ‭0.888‬‭which‬‭means‬‭the‬‭temperature‬‭strongly‬‭varies‬‭with‬‭the‬‭date.‬  ‭Hookworm‬‭Activity‬ ‭Independent‬‭Variable-‬‭Number‬‭of‬‭Hookworms‬ ‭Dependent‬‭Variable-‬‭amount‬‭of‬‭blood‬‭loss‬ ‭From‬‭the‬‭graph,‬‭it‬‭can‬‭be‬‭predicted‬‭that‬‭the‬‭individual‬‭would‬‭lose‬‭60mL‬‭if‬‭there‬‭were‬‭30‬‭hookworms.‬ ‭What‬‭type‬‭of‬‭data‬‭is‬‭presented‬‭in‬‭the‬‭hookworm‬‭graph?‬‭How‬‭did‬‭you‬‭come‬‭to‬‭that‬‭conclusion?‬ ‭-‬ ‭Discrete‬‭data‬ ‭-‬ ‭There‬‭are‬‭groups‬‭of‬‭information,‬‭and‬‭you‬‭cannot‬‭have‬‭0.1‬‭of‬‭a‬‭hookworm‬‭(not‬‭continuous).‬