Name (print neatly): Section #: First, write your name on this sheet and on the Scantron Card. The Physics faculty would like to help you do well:

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1 Name (prnt neatly): Secton #: Physcs 111 Exam Frst, wrte your name on ths sheet and on the Scantron Card. The Physcs faculty would lke to help you do well: 1. Budget your tme: 80 mnutes/0 questons=4 mn each.. Questons vary n dffculty. Look for ones you can do frst. 3. If you get stuck on a queston, move on. 4. All answers are n standard unts of m, s, kg and J. 5. If you show your work on the exam sheet you wll do better and the work wll mprove your ablty to study the exam afterward. 6. If any queston s unclear, ask a tutor to clarfy t mmedately. 7. Use a calculator. 8. Answers are approxmate. Select the closest one. Snce the NJIT Student Councl asks for scrupulous farness n exams, we remnd you that you have pledged to comply wth the provsons of the NJIT Academc Honor Code. The tutors wll help by allowng no devces wth nternet access. Sgnature: 1

2 1. Two blocks are on a horzontal, frctonless table. A force of.0 N pulls a block that has m=3.0 kg. The block s connected to a second block, M=4.0 kg, by a wre. What s the tenson, n N, n the wre? a. 1.1 b c. 0.9 d..0 e A beam s tlted up by 0.0 m at one end, and t s 1m long. Frcton s nsgnfcant. Mass of the glder s 1 kg. What s the magntude of the component of net force, n N, actng on the glder along the beam. a. 100 b. c. 5 d. 0.0 e An elevator of mass 1000 kg pulls down on one sde of a cable that goes over a pulley that has no frcton. A counter weght of 900 kg pulls on the other sde. The elevator starts to fall wth no frcton. What s the net force on the system, n N? Take the elevator s drecton of moton as postve. a. 50 b. 980 c. 100 d. 460 e. 0

3 4. On a Force table, forces are appled to a small rng near the center. If the forces are F1= j and F= j, what s the magntude, n N, of a thrd force whch wll keep the rng n equlbrum wthout touchng the pn at the center? a. 1. b. 1.6 c. 1.4 d. 0.9 e A crate of weght 100-N s sttng on a ramp wth a 30 degree slope, as shown. The playful man lets go and the crate sldes down wth no frcton and an acceleraton a1. He then places another crate of half the weght on the ramp. Agan, he lets go and the second crate sldes down wth acceleraton a. What are values of a1 and a n m/s? a. 9.8, 4.9 b. 4.9,.5 c. 9.8, 9.8 d. 4.9, 9.8 e. 4.9, The man lets go of the rope attached to the 100-N crate. It starts from rest and sldes down the 30-degree slope wth no frcton. The crate s velocty ncreases to 9.8 m/s at a tme t. What s t n s? a. 9.8 b c. 0.3 d..0 e

4 7. Two masses M 1 = kg and M = 4 kg are attached by a strng as shown. They start from rest and move wth no frcton untl they reach a velocty of 6.5 m/s. When do they reach that speed, n s? a b. 4.3 c..0 d. 1.4 e A lght fxture of mass 3.55 kg hangs by two wres (arranged lke a Y ), each of whch makes an angle of 10 degrees wth the celng. What s the tenson, n N, n one of the wres? a. 00 b. 100 c. 5 d. 0 e A lght fxture s suspended from a wall and a celng by wres, as shown. The tenson, T1 n wre 1 s 3.5 N. What s the mass, M, n kg? a. 3.4; b..0 c. 1.7 d e

5 10. A block sts on a horzontal surface wth a coeffcent of statc frcton of 0. between them. A horzontal force of 14 N s just able to move the block parallel to the surface. What s the mass, n kg, of the block? a. 7.1 b. 14 c. 70 d. 1.4 e Two masses are attached by a strng as shown. The mass, M, s 4 kg and the coeffcent of frcton s 0.5. What s the maxmum mass M 1, n kg, that allows the system to stay at rest? a. 0.3 b. c. 4 d. 0.5 e The block s at rest. Then, the ramp s gradually tlted. At at an angle of 14 degrees, the block begns to slde. What s the coeffcent of statc frcton between the block of unknown mass, m, and the ramp? a. Can t tell; need m b c d e

6 13. A woman pulls a block along a horzontal surface at a constant speed wth a 15-N force actng 0 above the horzontal. She does 85 J of work. How many meters does the block move? a. 5.6 b. 90 c. 6.0 d e A person does 00 J work lftng an object from the bottom of a well at a constant speed of.0 m/s n a tme of 5.1 s. What s the object s mass? (Neglect frcton.) a. 0 b..0 c. 6. d..1 e A woman throws a.0-kg ball from the orgn to a pont at (0 + 3 j + h k) meters, where k s the upward unt vector. The work done by the gravtatonal force on the ball s -90J. What s the heght, h? a. 19 b. 15 c. 39 d. 7 e

7 16. Suddenly, the drver of a fast car travellng 50 m/s sees a deer and slams on the brakes. The car travels for 10 s before t stops. What s the coeffcent of knetc frcton between the tres and the road? a b. 0.6 c. 0.3 d e An object falls vertcally downward n water at a constant speed. The vscosty of the water does work of -0 J as the object falls 0.80 m. What s the mass, n kg, of the object? a..0 b. 0 c. 3.7 d..6 e A constant force of ( -15 j + k) N acts on a partcle as t moves from the orgn to a pont (4 + 3 j + 5 k) m. How much work, n J, does the force do durng ths dsplacement? a. +30 b. 7 c. +45 d. 45 e

8 19. A CONSTANT force acts on an object and ncreases ts knetc energy, by 4 J. The object moves from (7-8 j +4 k)m to ( 11 5 j + 4 k) m. The net force actng on the object s equal to (Fx + 4 j + 5 k) N. What s Fx, n N. a. 1 b. -4 c. 4 d. 3 e As shown n the fgure, a block s pushed up aganst a vertcal wall by a force 0 N. The force s at an angle of 40 degrees from horzontal. The coeffcent of statc frcton between the block and the wall s Fnd the maxmum mass, n kg, that the force can prevent from sldng down. a. Infnte b. 0.9 c..1 d. 0.5 e. 10 8

9 Constants: 1 nch =.54 cm; 1 m =1.61 km; 1 cm=10 - m; 1 mm= 10-3 m; 1 gram=10-3 kg; g = 9.8 m/s 11 ; G = N m /kg 4 6 ; M Earth = kg ; R Earth = m 1D and D moton: x=x+vt (constant v); 1 1 x = x + vt + at ; v = v + at ; v = v + ax ( x) ; r = r + vt + at ; v = v + at Crcular moton: T = π R/ v ; T = π / ω ; a c = v / R Force: F = ma ; F1 = F1 ; Frcton: ff ss μμ ss NN ; ff kk = μμ kk NN Energes: KK = 1 mmvv ; UU gg = mmmmmm ; UU ss = 1 kkxx ; WW = FF ddrr = FF rr Etotal = K + Ug + US ; Emech = K+ Ug + Us = fd P = dw / dt = F v s K = W ; ; Momentum and Impulse: p = mv ; I = Fdt = p Center of mass: r mr / m ; v mv / m = cm = cm Collsons: p = const and E const (nelastc) or p = const and E= const (elastc) Rotatonal moton: ω = π /T ; ω = dθ / dt ; α = dω/ dt ; vt = rω ; at = rα ac = ar = vt / r = ω r ; atot = ar + a ; t vcm = rω (rollng, no slppng) ; acm = rα ω = ωo + αt ; θ = θ + ω t+ α f o t / ; ωf = ω + αθ ( f θ) = MR ; I MR I = MR /5; I pont hoop = ; I = MR /; dsk sphere I shell = MR /3; I rod ( center ) = ML / 1 Irod ( end ) = ML /3 ; I = mr ; I = Icm + Mh ; τ = r F ; τ = Iα ; L = r p ; L = Iω Energy: K rot = Iω / ; K = Krot + Kcm ; K + U = 0 ; W = τ θ ; Pnst = τω Flud: ρρ = MM ; PP = PP VV oo + ρρρρh ; AA 1 vv 1 = AA vv ; PP 1 + ρρρρyy ρρvv 1 = PP + ρρρρyy + 1 ρρvv ; BB = ρρ ffffffffff VV oooooooooooo gg Gm1m Gravtaton: F ˆ g = r 1 ; g() r = GM / r ; 1 r U = Gm m / r ; 4π 3 T = a GM 3 Math: 360 = π rad = 1 rev; Arc: s = rθ ; = 4 π R /3 ; = 4π R ; A = π R Vsphere Asphere b ± b 4ac quadratc formula to solve ax + bx + c = 0 : x = a Vectors: A= Aˆ ˆ x + Ay j ; Ax = A cos( θ ) ; Ay = A A y sn( θ ) ; A = Ax + Ay ; tanθ = Ax C = A+ B => Cx = Ax + Bx ; Cy = Ay + B ; y AA BB = AA BB cos θθ = AA xx BB xx + AA yy BB yy + AA zz BB zz ; ıı ıı = ȷȷ ȷȷ = kk kk = 1 ; ıı ȷȷ = ıı kk = ȷȷ kk = 0 A B= ABsnθ ; A B= ˆ( AB ) ˆ( ) ˆ y z AB z y + j AB z x AB x z + k( AB x y AB y x) ˆ ˆ= ˆj ˆj = kˆ kˆ= 0 ˆ ˆ ˆ ; j = k ˆ ˆ ˆ ; j k = ˆ ˆ ˆ ; k = j crcle 9