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Unformatted text preview: QM
SOLUTIOM§ ‘ Exam 2, continued. , Initials Section Number la. [10 pts] In Lab 3 you measured vertical forces and drew free—body diagrams for them. Here is a two—
dimensional situation, a cart on a sloped track tied to a post at the top of the track by means of a
string, as in the left—hand sketch below. Please draw vectors representing the forces acting on them
While they are in equilibrium, where friction is negligible. Clearly label each force using the form FA
0,13, where“A on B” means Object A acting on Object B. Please use the abbreviations C = cart, T =
track, S = string, and E = Earth. I
E; ‘ cmC Experimental set—up ’ t ' C ET mic me lb. [10 pts] Now please draw sketches of the reaction forces to each force drawn above, also using the
,fOITD PA on B. ' sin n 51 , 2 Points earned on this page: E HM Exam 2, continued. ' Initials Section Number 2a. [10 pts] Standing at the bottom of a slope, you give a momentary push to a block of mass m. It moves
up, then down, a slope of angle 6. You remain at the bottom of the slope, and bring it to a stop when it
returns to the bottom. The coefﬁcient of ﬁ'iction is u. Draw on the square on the right the vectors
representing the forces acting on the block while it moves down the slope and label them. Z. N ‘M (f) . Forces on block while it
Side view of block on a slope mOVes down the slope 2b. [10 pts] As you did for Experiment 4, write out Newton’s Second Law for the two directions
indicated by the coordinate system. Express your equations in terms of the lqiown variables m, g, 9,
and n, the unknown normal force N, and the unknown magnitude of acceleration a. erAl;N N_mj 9.33620 MassiwéeFg foal” FitMA] 2c. [10 pts] Sketch the vx(t) curve for the box ﬁom the moment it starts to move downthe slope to the
moment when you bring it to a stop. '= 3 3 Points earned on this page: [:1 '4m Exam 2, continued. ' Initials Section Number v 3a. [10 pts] You, mass m, are driving a car at constant speed v. The car ﬁrst moves along a horizontal
road, then up over a hill of constant radius R, as in the sketch below. Sketch and label the forces
acting upon you for the two situations: 1) whenthe car is traveling horizontally, and 2) when the car
is at the top of the hill. Also sketch a coordinate system. The pressUres from the seat on your back and
from the floOr on your feet are negligible. ' N.
I“ i “N i Horizo tal road Top 0 hill W'.Vw 3b. [10 pts] write out Newton’s Second Law for the two Situations, consistent with your coordinate
system. Your equations should be written in terms of m, V, R, g, Nb, the normal force on you while on
the horizontal road, and NI, the normal force on you While at the top of the hill. Hart;n<lil7' ’ Ell. V;
WWWA/la :0 .w—erm r _ R
‘MﬁINKZO W35Nt 5M% 4 ' Points earned on this page: 1:] AM Exam 2, continued. Initials Section Number 4a. [10 pts] During a ﬂight, while the plane is accelerating forward horizontally, you brace yourself by
grabbing the seat in front of you and pulling back on it horizontally, thereby steadying yourself '
against the seatbelt, as in the sketch on the left below. Sketch and label the forces acting upon you on
the box onthe right, using N, for the normal force of the back of the seat, Nc for the normal force
from the bottom cushion of the'seat, Ns for the normal (horizontal) force of the seatbelt, F}: for the magnitudeof your pull, and W for your weight. 4h. [10 pts] Sketch a coordinate system near the box above and label the directions. For each of the two
directions of your coordinate system write out Newton’s Second Law. (“oin H’Cﬂtf ‘ ‘ NONI/U130 7 _Nbi+1£;; “Mel‘mq 4c. [10 pts] IfW = 789 N, a = 3.21 m/sz, Fp = 54.3 N, and NS = 23.4 N what are N, and NC? Nor1U Nb: m0\*'l\}5'FP 'Nb: Nc=» 7‘80; l\/ i 5 Points earned on this page: (714/) Initials Section Number Exam 2, continued. . 1a. [10 pts] In Lab 3 you measured vertical forces and drew free—body diagrams for them. Here is a two— '
I dimensional situation, a cart on a slightly sloped track at rest due to static friction, as in the left—hand
sketch below. Please draw vectors representing the forces acting on them while they are in
equilibrium, where friction is negligible. Clearly label each force using the form FA “3, where “A on
B” means Object A acting on Object B. Please use the abbreviations C.= cart, T = track, S = string,
and E = Earth. 4 .FTmC Experimental Set—up lb. [10 ptsl Now please draw sketches of the reaction forces to each force drawn above, also using the
form PA on B. l ' 2 ' Points earned on this page: :1 W4, 2a. [10 pts] Standing at the bottom of a slope, you give a momentary push to a block of mass m. It moves
up a slope of angle 9. The coefﬁcient of friction is it. Draw on the square on the right the vectors
representing the forces acting on the block while it moves up the slope and label them. {\/ Exam 2, continued. ' Initials Section Number E Forces on block while it
Side view of block on a slope ' 7 moves up the slope 2b. [10 pts] As you did for Experiment 4, write out Newton’s Second Law for the two directions
indicated by the coordinate system. Express your equations in terms of the known variables m, g, 9,
and u, the unknown normal force N, and the unknown magnitude of acceleration a. :“ﬁill” NLEL‘T“
L” V * g; c me 20. [10 pts] Sketch the vx(t) curve for the box from the moment you start to give it a push up the slope to
the moment when it momentarily stops. ‘ v,g [In/s] 3 Points earned on this page: C] PM. Exam 2, continued; Initials Section Number 3a. [10 pts] You, mass m, are driving a car at constant speed v. The car first moves along a horizontal
roacl, then down into a valley of constant radius R, as in the sketch below. Sketch and label the forces
acting upon you for the two situations: 1) when the car is‘traveling horizontally, and 2) when the car
is at the bottom of the valley. The pressures from the seat on your batik and from the floor on your
feet are negligible. Also sketch a coordinate system. m a , WK")
Horizontal road Bottom of valley 3b. [10 pts] Write out Newton’s Second Law for the two’situations, consistent with your coordinate
system. Your equations should be written in terms of m, V, R, g, Nh, the normal force on you While on
the horizontal road: and Nb, the normal force on you while at the bottom of the valley. Plot—[mill ' 'W Va
.‘r—ijvro , ' Nb "Mjme’ 4  Points earned on this page: 1:: PM Exam 2, continued. Initials Section Number 4a. [10 pts] During a ﬂight, While the plane is slowing down but staying at the same altitude, you brace
yourself by grabbing the Seat in front of you and pushing on it horizontally, thereby reducing (but not
eliminating) the tension in the seatbelt, as in the sketch on the left below. Sketch and label the forces
acting upon you on the box on the right, using N, for the normal force of the back of the seat, Nc for
the normal force from the bottom’cushion of the seat, NS for the normal (horizontal) force of the
seatbelt, RS for the reaction force from the forward seat, and W for your weight. 4h. [10 pts] Sketch a coordinate system near the box above and label the directions. For each of the two
directions of your coordinate system, write out Newton’ 3 Second Law. ’ Polit 4 Xudlr
We‘l/‘j :0 R31‘klsﬂubzmq (as : 54.3w 4c. [10 pts] If a = 3.21m/SZ,FP = 54.3 N, Nc = 789 N, and N, = 23.4 N what are W and NS? Nail/V ' , N'Z'Wla’twgﬂﬁs S M:737M ' ; %q+f\lp'ﬁ> N5 : 23% N
W= ‘75"?A/
Ns= gait/V 5 Points earned on this page: ...
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 Fall '08
 Kiel
 mechanics

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