PHYS 141 EXAM 2 CONCEPT
QUESTIONS WITH CORRECT ANSWERS
The bbmass bbof bbthe bbmoon bbis bb1/81 bbof bbthe bbmass bbof bbthe bbearth. bbCompared
bbto bbthe bbgravitational bbforce bbthat bbthe bbearth bbexerts bbon bbthe bbmoon, bbthe
bbgravitational bbforce bbthat bbthe bbmoon bbexerts bbon bbthe bbearth bbis bb- bbAnswer
bbequally bbstrong.
Compared bbto bbthe bbearth, bba bbdistant bbplanet bbhas bbtwice bbthe bbmass bband bbtwice
bbthe bbradius. bbThis bbmeans bbthat bbcompared bbto bbthe bbearth's bbsurface bbgravity,
bbthe bbsurface bbgravity bbon bbthe bbother bbplanet bbis bb- bbAnswer bbhalf bbas bbmuch.
A bbbox bbis bbsitting bbin bbthe bbback bbof bbthe bbtruck. bbThe bbtruck bbbegins bbto
bbaccelerate bbforward bb(to bbthe bbright) bband bbthe bbbox bbdoes bbnot bbslip. bbIn bba
bbfree-body bbdiagram bbfor bbthe bbbox, bbthe bbforce bbof bbfriction bbon bbthe bbbox bbpoints
bb- bbAnswer bbto bbthe bbright.
A bbcable bbattached bbto bba bbcar bbholds bbthe bbcar bbat bbrest bbon bbthe bbfrictionless
bbramp. bbThe bbramp bbexerts bba bbnormal bbforce bbon bbthe bbcar. bbHow bbdoes bbthe
bbmagnitude bbFn bbof bbthe bbnormal bbforce bbcompare bbto bbthe bbweight bbof bbthe bbcar?
bb- bbAnswer bbFn bb< bbw
An bbobject bbis bbthrown bbup bbin bbthe bbair. bbIs bbthe bbobject bbin bbmomentary
bbequilibrium bbwhen bbit bbreaches bbits bbhighest bbpoint? bb- bbAnswer bbNo, bbnever.
*equilibrium bb= bbzero bbacceleration*
You bbpress bbyour bbphysics bbbook bbflat bbagainst bba bbvertical bbwall bbwith bbyour
bbhand. bbYour bbarm bbremains bbhorizontal. bbWhat bbis bbthe bbdirection bbof bbthe bbfriction
bbforce bbexerted bbby bbthe bbwall bbon bbthe bbbook? bb- bbAnswer bbupward
You bbdrive bba bbrace bbcar bbaround bba bbcircular bbtrack bbof bbradius bbR bbat bba
bbconstant bbspeed bbof bbv. bbIf bbyou bbthen bbdrive bbthe bbsame bbcar bbaround bba
bbdifferent bbcircular bbtrack bbof bbradius bb2R bbat bba bbconstant bbspeed bbof bb2v, bbyour
bbacceleration bbwill bbbe bb- bbAnswer bbtwice bbas bbgreat.
Consider bbthe bbfollowing bbsituations:
(i) bbA bbminivan bbis bbfollowing bba bbhairpin bbturn bbon bba bbmountain bbroad bbat bba
bbconstant bbspeed bbof bbtwenty bbmiles bbper bbhour.
(ii) bbA bbparachutist bbis bbdescending bbat bba bbconstant bbspeed bbof bb10 bbm/s. bb
(iii) bbA bbheavy bbcrate bbhas bbbeen bbgiven bba bbquick bbshove bband bbis bbnow bbsliding
bbacross bbthe bbfloor. bbThere bbis bbfriction bbbetween bbthe bbcrate bband bbfloor.
(iv) bbA bbchild bbis bbswinging bbback bband bbforth bbon bba bbswing bbat bbthe bbpark.
, (v) bbA bbfootball bbthat bbwas bbkicked bbis bbflying bbthrough bbthe bbgoal bbposts. bb
In bbwhich bbone bbof bbthese bbsituations bbdoes bbthe bbobject bbor bbperson bbexperience
bbzero bbacceleration? bb- bbAnswer bbii bbonly
A bbping-pong bbball bbis bbshot bbinto bba bbcircular bbtube bbthat bbis bblying bbflat
bb(horizontal) bbon bba bbtabletop. bbWhen bbthe bbping-pong bbball bbleaves bbthe bbtrack,
bbwhich bbpath bbwill bbit bbfollow? bb- bbAnswer bbThe bbpath bbtangential bbto bbthe bbtabletop
A bbpendulum bbbob bbof bbmass bbm bbis bbattached bbto bbthe bbceiling bbby bba bbthin bbwire
bbof bblength bbL. bbThe bbbob bbmoves bbat bba bbconstant bbspeed bbin bba bbhorizontal
bbcircle bbof bbradius bbR, bbwith bbthe bbwire bbmaking bba bbconstant bbangle bbB bbwith bbthe
bbvertical. bbThe bbtension bbin bbthe bbwire bb- bbAnswer bbis bbgreater bbthan bbmg.
You bbare bbriding bbin bbthe bbforward bbpassenger bbseat bbof bba bbcar bbas bbit bbtravels
bbalong bba bbstraight bbportion bbof bbhighway. bbThe bbcar bbcontinues bbtraveling bbat bba
bbconstant bbspeed bbas bbit bbfollows bba bbsharp, bbunbanked bbcurve bbto bbthe bbleft. bbYou
bbfeel bbthe bbdoor bbpushing bbon bbthe bbright bbside bbof bbyour bbbody. bbWhich bbof bbthe
bbfollowing bbforces bbin bbthe bbhorizontal bbdirection bbare bbacting bbon bbyou? bb- bbAnswer
bb-a bbstatic bbfrictional bbforce bbbetween bbyou bband bbthe bbseat
-a bbnormal bbforce bbof bbthe bbdoor
NOT bba bbforce bbpushing bbyou bbtoward bbthe bbdoor
The bbearth bbis bba bbsatellite bbof bbthe bbsun. bbSuppose bbthe bbsun bbwere bbto bbshrink
bbto bbhalf bbof bbits bbpresent bbradius bbwhile bbmaintaining bbthe bbsame bbmass. bbWhat
bbeffect bbwould bbthis bbhave bbon bbthe bbradius bbr bband bbthe bbperiod bbT bbof bbthe
bbearth's bborbit bbaround bbthe bbsun? bb- bbAnswer bbr bband bbT bbwould bbboth bbbe
bbunchanged.
The bbMoon bbdoes bbnot bbcrash bbinto bbEarth bbbecause bb- bbAnswer bbof bbits bbhigh
bbspeed bbtangential bbto bbits bbpath. bbIf bbit bbslowed bbdown bbor bbstopped bbmoving bball
bbtogether, bbit bbwould, bbof bbcourse, bbfall bbdirectly bbinto bbEarth. bbWith bbits bbhigh
bbspeed, bbthe bbMoon bbwould bbfly bboff bbinto bbspace bbif bbit bbweren't bbfor bbgravity
bbproviding bbthe bbcentripetal bbforce.
An bbelevator bbis bbbeing bblifted bbat bba bbconstant bbspeed bbby bba bbsteel bbcable
bbattached bbto bban bbelectric bbmotor. bbWhich bbstatement bbis bbcorrect? bb- bbAnswer
bbThe bbcable bbdoes bbpositive bbwork bbon bbthe bbelevator, bband bbthe bbelevator bbdoes
bbnegative bbwork bbon bbthe bbcable.
A bbtractor bbdriving bbat bba bbconstant bbspeed bbpulls bba bbsled bbloaded bbwith bbfirewood.
bbThere bbis bbfriction bbbetween bbthe bbsled bband bbthe bbroad. bbThe bbtotal bbwork bbdone
bbon bbthe bbsled bbafter bbit bbhas bbmoved bba bbdistance bbd bbis bb- bbAnswer bbZero.
Assuming bba bbcircular bborbit, bbthe bbwork bbdone bbby bbthe bbgravitational bbforce
bbexerted bbon bbthe bbEarth bbby bbthe bbSun bbduring bba bbshort bbtime bbinterval bbin
QUESTIONS WITH CORRECT ANSWERS
The bbmass bbof bbthe bbmoon bbis bb1/81 bbof bbthe bbmass bbof bbthe bbearth. bbCompared
bbto bbthe bbgravitational bbforce bbthat bbthe bbearth bbexerts bbon bbthe bbmoon, bbthe
bbgravitational bbforce bbthat bbthe bbmoon bbexerts bbon bbthe bbearth bbis bb- bbAnswer
bbequally bbstrong.
Compared bbto bbthe bbearth, bba bbdistant bbplanet bbhas bbtwice bbthe bbmass bband bbtwice
bbthe bbradius. bbThis bbmeans bbthat bbcompared bbto bbthe bbearth's bbsurface bbgravity,
bbthe bbsurface bbgravity bbon bbthe bbother bbplanet bbis bb- bbAnswer bbhalf bbas bbmuch.
A bbbox bbis bbsitting bbin bbthe bbback bbof bbthe bbtruck. bbThe bbtruck bbbegins bbto
bbaccelerate bbforward bb(to bbthe bbright) bband bbthe bbbox bbdoes bbnot bbslip. bbIn bba
bbfree-body bbdiagram bbfor bbthe bbbox, bbthe bbforce bbof bbfriction bbon bbthe bbbox bbpoints
bb- bbAnswer bbto bbthe bbright.
A bbcable bbattached bbto bba bbcar bbholds bbthe bbcar bbat bbrest bbon bbthe bbfrictionless
bbramp. bbThe bbramp bbexerts bba bbnormal bbforce bbon bbthe bbcar. bbHow bbdoes bbthe
bbmagnitude bbFn bbof bbthe bbnormal bbforce bbcompare bbto bbthe bbweight bbof bbthe bbcar?
bb- bbAnswer bbFn bb< bbw
An bbobject bbis bbthrown bbup bbin bbthe bbair. bbIs bbthe bbobject bbin bbmomentary
bbequilibrium bbwhen bbit bbreaches bbits bbhighest bbpoint? bb- bbAnswer bbNo, bbnever.
*equilibrium bb= bbzero bbacceleration*
You bbpress bbyour bbphysics bbbook bbflat bbagainst bba bbvertical bbwall bbwith bbyour
bbhand. bbYour bbarm bbremains bbhorizontal. bbWhat bbis bbthe bbdirection bbof bbthe bbfriction
bbforce bbexerted bbby bbthe bbwall bbon bbthe bbbook? bb- bbAnswer bbupward
You bbdrive bba bbrace bbcar bbaround bba bbcircular bbtrack bbof bbradius bbR bbat bba
bbconstant bbspeed bbof bbv. bbIf bbyou bbthen bbdrive bbthe bbsame bbcar bbaround bba
bbdifferent bbcircular bbtrack bbof bbradius bb2R bbat bba bbconstant bbspeed bbof bb2v, bbyour
bbacceleration bbwill bbbe bb- bbAnswer bbtwice bbas bbgreat.
Consider bbthe bbfollowing bbsituations:
(i) bbA bbminivan bbis bbfollowing bba bbhairpin bbturn bbon bba bbmountain bbroad bbat bba
bbconstant bbspeed bbof bbtwenty bbmiles bbper bbhour.
(ii) bbA bbparachutist bbis bbdescending bbat bba bbconstant bbspeed bbof bb10 bbm/s. bb
(iii) bbA bbheavy bbcrate bbhas bbbeen bbgiven bba bbquick bbshove bband bbis bbnow bbsliding
bbacross bbthe bbfloor. bbThere bbis bbfriction bbbetween bbthe bbcrate bband bbfloor.
(iv) bbA bbchild bbis bbswinging bbback bband bbforth bbon bba bbswing bbat bbthe bbpark.
, (v) bbA bbfootball bbthat bbwas bbkicked bbis bbflying bbthrough bbthe bbgoal bbposts. bb
In bbwhich bbone bbof bbthese bbsituations bbdoes bbthe bbobject bbor bbperson bbexperience
bbzero bbacceleration? bb- bbAnswer bbii bbonly
A bbping-pong bbball bbis bbshot bbinto bba bbcircular bbtube bbthat bbis bblying bbflat
bb(horizontal) bbon bba bbtabletop. bbWhen bbthe bbping-pong bbball bbleaves bbthe bbtrack,
bbwhich bbpath bbwill bbit bbfollow? bb- bbAnswer bbThe bbpath bbtangential bbto bbthe bbtabletop
A bbpendulum bbbob bbof bbmass bbm bbis bbattached bbto bbthe bbceiling bbby bba bbthin bbwire
bbof bblength bbL. bbThe bbbob bbmoves bbat bba bbconstant bbspeed bbin bba bbhorizontal
bbcircle bbof bbradius bbR, bbwith bbthe bbwire bbmaking bba bbconstant bbangle bbB bbwith bbthe
bbvertical. bbThe bbtension bbin bbthe bbwire bb- bbAnswer bbis bbgreater bbthan bbmg.
You bbare bbriding bbin bbthe bbforward bbpassenger bbseat bbof bba bbcar bbas bbit bbtravels
bbalong bba bbstraight bbportion bbof bbhighway. bbThe bbcar bbcontinues bbtraveling bbat bba
bbconstant bbspeed bbas bbit bbfollows bba bbsharp, bbunbanked bbcurve bbto bbthe bbleft. bbYou
bbfeel bbthe bbdoor bbpushing bbon bbthe bbright bbside bbof bbyour bbbody. bbWhich bbof bbthe
bbfollowing bbforces bbin bbthe bbhorizontal bbdirection bbare bbacting bbon bbyou? bb- bbAnswer
bb-a bbstatic bbfrictional bbforce bbbetween bbyou bband bbthe bbseat
-a bbnormal bbforce bbof bbthe bbdoor
NOT bba bbforce bbpushing bbyou bbtoward bbthe bbdoor
The bbearth bbis bba bbsatellite bbof bbthe bbsun. bbSuppose bbthe bbsun bbwere bbto bbshrink
bbto bbhalf bbof bbits bbpresent bbradius bbwhile bbmaintaining bbthe bbsame bbmass. bbWhat
bbeffect bbwould bbthis bbhave bbon bbthe bbradius bbr bband bbthe bbperiod bbT bbof bbthe
bbearth's bborbit bbaround bbthe bbsun? bb- bbAnswer bbr bband bbT bbwould bbboth bbbe
bbunchanged.
The bbMoon bbdoes bbnot bbcrash bbinto bbEarth bbbecause bb- bbAnswer bbof bbits bbhigh
bbspeed bbtangential bbto bbits bbpath. bbIf bbit bbslowed bbdown bbor bbstopped bbmoving bball
bbtogether, bbit bbwould, bbof bbcourse, bbfall bbdirectly bbinto bbEarth. bbWith bbits bbhigh
bbspeed, bbthe bbMoon bbwould bbfly bboff bbinto bbspace bbif bbit bbweren't bbfor bbgravity
bbproviding bbthe bbcentripetal bbforce.
An bbelevator bbis bbbeing bblifted bbat bba bbconstant bbspeed bbby bba bbsteel bbcable
bbattached bbto bban bbelectric bbmotor. bbWhich bbstatement bbis bbcorrect? bb- bbAnswer
bbThe bbcable bbdoes bbpositive bbwork bbon bbthe bbelevator, bband bbthe bbelevator bbdoes
bbnegative bbwork bbon bbthe bbcable.
A bbtractor bbdriving bbat bba bbconstant bbspeed bbpulls bba bbsled bbloaded bbwith bbfirewood.
bbThere bbis bbfriction bbbetween bbthe bbsled bband bbthe bbroad. bbThe bbtotal bbwork bbdone
bbon bbthe bbsled bbafter bbit bbhas bbmoved bba bbdistance bbd bbis bb- bbAnswer bbZero.
Assuming bba bbcircular bborbit, bbthe bbwork bbdone bbby bbthe bbgravitational bbforce
bbexerted bbon bbthe bbEarth bbby bbthe bbSun bbduring bba bbshort bbtime bbinterval bbin
