Physics 111 Final Exam, Fall 2013, Version A

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1 Physcs 111 Fnal Exam, Fall 013, Verson A Name (Prnt): 4 Dgt ID: Secton: Honors Code Pledge: For ethcal and farness reasons all students are pledged to comply wth the provsons of the NJIT Academc Honor Code. You must answer the exam questons entrely by yourself. Turn off all cell phones, pagers, or other communcaton devces. Use only your own calculator. A Instructons: Frst, wrte your name and secton number on both the Scantron card and ths exam sheet. Use the formula sheet (last exam booklet page) and no other materals. Budget your tme. There are 9 multple choce problems. Answer each queston on the Scantron card usng # pencl. Also crcle your answers on queston papers. Do not hestate to ask for clarfcaton of any exam queston, f needed, from your proctor or Professor. 1. A 1.-kg object movng wth a speed of 8.0 m/s colldes perpendcularly wth a wall and emerges wth a speed of 6.0 m/s n the opposte drecton. If the object s n contact wth the wall for.0 ms, what s the magntude of the average force on the object by the wall? A) 9.8 kn B) 8.4 kn C) 7.7 kn D) 9.1 kn E) 1. kn. A 5.0-kg mass wth an ntal velocty of 4.0 m/s, east colldes wth a 4.0-kg mass wth an ntal velocty of 3.0 m/s, west. After the collson the 5.0-kg mass has a velocty of 1. m/s, south. What s the magntude of the velocty of the 4.0-kg mass after the collson? A).0 m/s B) 1.5 m/s C) 1.0 m/s D).5 m/s E) 3.0 m/s 3. A body oscllates wth smple harmonc moton along the x axs. Its dsplacement vares wth tme accordng to the equaton x(t) = (5.0 m) sn [( s -1 ) t + /3]. The velocty (n m/s) of the body at t = 1.0 s s A) +7.9 B) -7.9 C) -14 D) +14 E) -5.0 Page 1 of 9

2 4. The ampltude of a system movng wth smple harmonc moton s doubled. The total energy wll then be A) 4 tmes as large B) 3 tmes as large C) tmes as large D) the same as t was E) half as much 5. The mass n the fgure sldes on a frctonless surface. If m = kg, k = 800 N/m, the frequency of oscllaton (n Hz) s approxmately A) 6.3 B) 4.8 C) 3. D) 17.1 E) The system n the fgure s n equlbrum. A concrete block of mass 5 kg hangs from the end of the unform strut whose mass s 46.0 kg. What s the magntude of the tenson T n the cable? A).43 kn B) 3.44 kn C) 4.86 kn D) 6.64 kn E) 7.6 kn 7. In the Problem 6, what s the magntude of the force on the strut from the hnge? A).43 kn B) 5.75 kn C) 8.9 kn D) 8.83 kn E) kn 8. An asterod, headed drectly toward Earth, has a speed of 1 km/s relatve to the planet when t s at a dstance of 10 Earth rad from Earth's center. Neglectng the effect of Earth's atmosphere on the asterod, fnd the asterod's speed when t reaches Earth's surface. The earth's radus and mass are R E = m and m E = kg. A) 16 km/s B) 1 km/s C) 6 km/s D) 10 km/s E) 0 km/s Page of 9

3 9. Three unform spheres of masses m 1 =.00 kg, m = 4.00 kg, and m 3 = 6.00 kg are placed at the corners of a rght trangle as shown n the fgure. Calculate the resultant gravtatonal force on the object of mass m, assumng the spheres are solated from the rest of the Unverse. A) N B) N C) N D) N E) N 10. A planet moves n an ellptcal orbt wth the Sun at one focus. At what pont does the planet move the fastest? 11. Three forces are actng on a mass of kg as shown n the fgure. The magntudes of the forces are F 1 =10 N, F =5 N, and F 3 =7 N. What s the magntude of the net acceleraton of the mass? y A) none of the other answers B) 4.5 m/s C) 1.5 m/s D) 3.7 m/s E) 3.0 m/s F 75 0 F x F 3 1. Two blocks ( m 1 =kg, m =3kg) are pushed along a frctonless horzontal surface by an external force of magntude F=10N. Calculate the magntude of the force of m 1 on m. A) 10 N B) 5 N C) N D) 4 N E) none of the above (6 N) F m 1 m Page 3 of 9

4 13. The mass n the fgure s fallng at CONSTANT speed. What s the coeffcent of frcton f m 1 = kg, m =1.8 kg, and the angle of the nclne s 40 degrees? The pulley s frctonless and massless. A) 0. B) 0.54 C).3 D) 0.61 E) none of the other answers 14. An object of mass 0.kg s ted to a strng 0.5 m long and swung n a vertcal crcle at constant velocty. If the speed of the mass s 3.0 m/s, what s the tenson n the strng when the mass s at the HIGHEST poston n the vertcal crcle? A) 1.6 N B).0 N C) 5.6 N D) 3.6 N E) None of the other answers 15. At t = 0, a wheel rotatng about a fxed axs at a constant angular acceleraton has an angular velocty of.0 rad/s. Two seconds later t has turned through 5.0 complete revolutons. What s the angular acceleraton of ths wheel? A) 17 rad/s B) 14 rad/s C) 0 rad/s D) 3 rad/s E) 13 rad/s 16. In the fgure below, a dsk (radus R = 1.0 m, mass =.0 kg) s suspended from a pvot a dstance d = 0.5 m above ts center of mass. The moment of nerta (n kgm ) s approxmately A) 0.15 B) 0.50 C) 0.45 D) E) A frctonless pulley free to rotate about a frctonless axle has a radus R = 0.1 m and a moment of nerta I = kg m. A 1.5-kg object s attached to a very lght wre that s wrapped around the rm of the pulley. The system s released from rest and mass m moves downward a dstance of 63.7 cm. Fnd the angular velocty of the pulley at ths nstant. A) 8.4 rad/s B) 5.75 rad/s C) 16. rad/s D) 0.5 rad/s E) 3. rad/s Page 4 of 9

5 18. A thn rod of mass M = 1. kg and length d = m s struck at one end by a ball of clay of mass m = kg, movng wth speed v 0 =7.5 m/s as shown n the fgure. The ball stcks to the rod. After the collson, the angular velocty of the clay-rod system about O, the mdpont of the rod, s A) 0.5 rad/s B) 1.1 rad/s C) 0.83 rad/s D).8 rad/s E) 4.0 rad/s 19. If and, what s the magntude of the vector? A) 4 B) 0 C) 448 D) 903 E) A proton movng along the x axs has an ntal speed n the postve x drecton of m/s and a constant acceleraton n the postve x drecton of m/s. What s the velocty of the proton after t has traveled a dstance of 80 cm? A) m/s B) m/s C) m/s D) m/s E) m/s 1. At t = 0, a partcle leaves the orgn wth a velocty of 9.0 m/s n the postve y drecton and moves n the xy plane wth a constant acceleraton of ( j) m/s. At the nstant the x coordnate of the partcle s 15 m, what s the speed of the partcle? A) 16 m/s B) 5.7 m/s C) 1 m/s D) 14 m/s E) 6 m/s. A car travels counterclockwse around a flat crcle of radus 0.5 km at a constant speed of 0 m/s. When the car s at pont A as shown n the fgure, what s the car's acceleraton? A) 1.6 m/s, south Page 5 of 9

6 B) Zero C) 1.6 m/s, east D) 1.6 m/s, north E) 1.6 m/s, west 3. In the fgure, a 700-kg crate s on a rough surface nclned at 30. A constant external force P = 5600 N s appled horzontally to the crate. As the force pushes the crate a dstance of 3.00 m up the nclne, the speed changes from 1.40 m/s to.50 m/s. How much work does gravty do on the crate durng ths process? A) -10,300 J B) -3,400 J C) 10,300 J D) 3,400 J E) Zero 4. A chld pulls on a wagon wth a horzontal force of 75 N. If the wagon moves horzontally a total of 4 m n 3.0 mn. what s the average power generated by the chld? A) 18 W B) W C) 4 W D) 7 W E) Zero 5. A 0-N crate startng at rest sldes down a rough 5.0-m long ramp, nclned at 5 wth the horzontal. 0 J of energy s lost to frcton. What wll be the speed of the crate at the bottom of the nclne? A) 0.98 m/s B) 1.9 m/s C) 3. m/s D) 4.7 m/s E) 0.7 m/s 6. A smple pendulum, 1.00 m n length, s released from rest when the support strng s at an angle of 35.0 from the vertcal. What s the speed of the suspended mass at the bottom of the swng? (g = 9.80 m/s and gnore ar resstance) A) 0.67 m/s B) 0.94 m/s C) 1.33 m/s D) 1.88 m/s E) 1.55 m/s Page 6 of 9

7 7. A hypodermc syrnge contans water. The barrel of the syrnge has a cross-sectonal area A=.5 x 10-5 m, and the needle has a cross-sectonal area a=1.00 x 10-8 m. In the absence of a force on the plunger, the pressure everywhere s 1.00 atm. When a force of magntude.00 N acts on the plunger, what s the speed of water as t leaves the needle. A) 5.7 m/s B) 1.65 m/s C) 1.53 m/s D) 15.5 m/s E).5 m/s 8. A sold rock, suspended n ar by a sprng scale, has a measured mass of 9.00 kg. When the rock s submerged n water, the scale reads 3.30 kg. What s the densty of the rock? (water densty = 1,000 kg/m 3 ). A) kg/m 3 B) kg/m 3 C) kg/m 3 D) kg/m 3 E) kg/m 3 9. An deal flud flows through a ppe made of two sectons wth dameters of 1.0 and 3.0 nches, respectvely. The speed of the flud flow through the 3.0-nch secton wll be what factor tmes that through the 1.0-nch secton? A) 6.0 B) 9.0 C) 1/3 D) 1/9 E) 1/ Page 7 of 9

8 FORMULAS Fnal Exam Converson Factors: 1 nch =.54 cm; 1 m = m; 1 cm=10 - ; 1 mm= 10-3 m; 1 g=10-3 kg; Physcal constants: g 9.8 m/s 11 ; G N m /kg 4 6 ; M Earth kg ; REarth m 3 Math: 360 = radans = 1 revoluton. Arc length s r ; Vsphere 4 R /3 ; Asphere 4 R ; Acrcle R b b 4ac quadratc formula to solve ax bx c 0 : x a Vectors: A Aˆ ˆ x Ay j ; Ax A cos( ) ; Ay A A y sn( ) ; A Ax A ; tan y Ax C AB mples Cx Ax Bx ; Cy Ay By ; ; AB A B sn ; ABˆ( A ) ˆ( ) ˆ ybz AzBy j AzBx AxBz k( AxBy AyBx) ˆˆ ˆj ˆj kˆkˆ 0 ; ˆ ˆj kˆ ; ˆj kˆ ˆ; k ˆ ˆ ˆ j 1D and D moton: r v dx dv d r vavg ; aavg ; v ; a t t dt dt dt 1 1 x x vt at ; vv at ; v v a( x x) ; r r vt at ; v v at Crcular moton: T R/ v ; T / ; a c v / R Newtons Laws: F ma ; F1 F1 Frcton: ; Energes: ; ; ; W F dr F r Etotal K Ug US E ; mech KUg Us fsd P dw / dt F v K W ; ; Momentum and Impulse: p mv ; I Fdt p Center of mass: rcm mr / m ; vcm mv / m Collsons: p = const and E const (nelastc) or p = const and E= const (elastc) Rotatonal moton: /T ; d / dt ; d / dt ; vt r ; at r ac ar vt / r r atot ar at ; v cm r (rollng, no slppng) ; acm r o t ; t t f o / ; f ( f ) I pont MR ; Ihoop MR ; I dsk MR / ; Isphere MR /5 ; Ishell MR /3 ; Irod ( center ) ML /1 I ML ; I mr ; I I Mh ; r F ; I ; L I rod ( end ) /3 Energy: Krot cm ; L r p I / ; K Krot Kcm ; K U 0 ; W ; Pnst Flud: ; ; ; Gm1m Gravtaton: F ˆ g r 1 ; gr () GM/ r ; 1 r U Gmm / r; 4 T a GM 3 Page 8 of 9

9 Oscllatory moton: ; ; ; Page 9 of 9