G* 111... · PHYS 111-002/Midterm f2-Page2of6- (2o*) 3.A ball rolls counterclockwise around the inside of a horizontal pipe.The ball is fastest at the lowest point, slowest at the

PHYSICS 111_OO2

Nov. 4, 2013 - 10:30 to 11:20

Midterm f2 r\T^*^. T^ka E brwsk tl\ame:

Student Number: Soltn (

Midterm (32points)Multiple Choice: Select the best answer for each of the following questions. Put a circle aroundyour final answer.

(2o*) 1. You awake in the night to find that your living room is on fire. Your one chance to save yourselfis to throw something that will hit the back of your bedroom door and close it, giving you afew seconds to escape out the window. You happen to have both a sticky bali of clay and asuper-bouncy Superball next to your bed, both the same size and same mass. You only havetime to throw one. Which will it be? Your life depends on making the right choice!

aG) Throw the Superbatt.

Y Throw rhe ball of clay.

(c) It doesn't matter. Throw either.-J -\ -tf, = P**P),Jrl"[, ft =MV,-

F*=o(sn*tt)

= -MV,

fubky ;.\Fi = MV,

Ff = *rnv>J

4- rcNvLei oltt't

J *tvt (V tV),S tp4 (V1tVu)

tvt r

tr"yrln o^ luv ts rl{hvt

(a) 43.3 N, down the incline

re 25 N, up the incline(c) 10 N, down the incline(d) 30.3 N, up the incline(") 50 N, down the incline

f S P o{ blout< '

{v1i

'/\ E

+, WWoLtvl 0* ttsl

{rz wrTstvr\ 3 X7-5N TMclrw('

l*prlrc on

bd

ii- = - MVt -Yt4 Vt =

fuwynla Dn looY(2o*) 2. A mass of 5 kg sits at rest on an incline making an angle of 30o with respect to horizontat. If

l-ts:0.7, what is the friction force on the block? Choose the best answer.

G* lauyn ir^y",l koq Joov u/Lr/t^ tt(tuybowncrtr boil "

8* rJ)* -rI s, rntnx '/r{l = 7us fianco{ t = 41"1 N{t 1 {rtma,t< ,

ln *ht 5 <xava.p k ,

PHYS 111-002/Midterm f2 -Page2of6-

(2o*) 3. A ball rolls counterclockwise around the inside of a horizontal pipe. The ball is fastest at thelowest point, slowest at the highest point. At the point shown, with the ball moving down (thegreen arrow shows the ball's instantaneous velocity), what is the direction of the net force onthe ball?

C.

\

@

A ,Lw l' Y;Y d nll' '

A"

<apr

B.

***".1r,*t Priivvt {k, , fo I ,^ (

t," tU,t 5 Ctt*< :

d .cu,qt<E ott'f frt of b*tl

6

E.

?eD * b^ll

vba

lrc%

r^i c,*scs ft.( of lil)1o cha,^V< ,

Mw^tr%\*

tf n^ is ln, svu"fl,

Y ft7!r y,tlvl Trt"tloF( {, nil^s+ oyprr<-t hrl rnnotiru .

f4l'nr

+, k or l*ry at!

(- h^,t4 fr =t,** -/rh

'*ttmf cot0

PHYS 111-002/Midterm f2 - Page 3 of 6 -

FYee Response: Write out complete answers to the following questions. Include diagrams whereappropriate. Show your work since it allows us to award partial credit.

(rOo'"; 4. The figure shows a block of mass rn resting on a 20o slope. The coefficient of static frictionbetween the block and the sloped surface is 0.80. It is connected via a massless string over amassless, frictionless pulley to a hanging block of mass 2.0 kg.

What is the mintmum vaiueof rn such that the system remains at rest? To receive full credit,your solution must include free body diagrams for each of the masses.

FBD

I

M L, tYYt4tlvt

.' -- {^Etkr L\=D -- T* ^ry

wqn{ {,yos*bl<_

,r- - ''t vv<ta!

.)u>7

Lfr:o ; T*tnVsmo -ftfeU M r:

I

I , *rl, u/ctno -,urn/caso =o"t ----'4 r

M6coS0

i Qc,t.o) l<.,JE

/a-'I

rhfi

rlafl srn

Yl - W't"oS 0

Mffco so

,!r= I."VJ6' ],,o "

,us -- D.Eoi, *)ao

TYr,,=o; H * is {eEE t1+ua t.E3 k7, tt*r.-

n=

,ToJt+ K'o

Sth9 Tsco{(,

:u^1"1. {o

PHYS 111-002/Midterm f2 - Page 4 of 6 -

(8o*) 5. Mass rh on tlne horizontal frictionless table of the figure is connected by a string through ahole in the table to a hanging mass rnz. With what angular speed a.r must rnl rotate in a circleof radius r if. m2 is to remain hanging at rest? Find an expression for r.,, in terms of rnL) m2 j r,and g.

FND ruz:

trIq

I

I

J tnrX

Lru'N

FBP !v11',

,rt, 6

a3/fii}t

-f : (Arctr =

u)t= _f_hrr

*u^".ToJa- Frb*wtkl; Srl'n {

MdLYI

y_Lh+r f

A

\^

T

({rrt hr"(rrr)

Lr,:

N=Vf

Tf = hrv'

M7q...-.ftnt y

frldv^,nf^w lq

-u lhz q.

rvl i=t !=

z'>O 1-

X = Vc -a?^X"x W&twtyt.t

:

zgLa.

*^^",TJq Erl^t*il<i, Sa{r n t

Vs = ffivr=#

Vi = 1.0( nl (

T= ?.al vt/s>

PHYS 111-002/Midterm S2 -Page5of6-

(8o*) 6. The Japanese flying squid is able to 'Jump" off the surface of the sea by taking water into itsbody cavity and then ejecting the water vertically downward. A squid is able to eject 0.30 kgof water with a speed of 20.0 m/s. Without any water in its cavity, the mass of the squid is0.85 kg.

(a) If starting from rest at the surface of the sea, what will be the speed of the squid immediatelyafter ejecting the water? (b) How high above the surface of the sba will the squid rise?

(") Lovtgcvt,r*ia yr ofUoWr't\\^^^ '

llut ir ('L< 6Lu.

e\lo(ri,:r't y r able vu -

-J

(nn, r rn )y' = Mwi^ *,*o'vtf{r1. rc 6l-"

-\MsVs

O = -fn, V,I

wc^*w cjt.<'ttJ

f W\s Vs

Jnnrrrtnlr.,* d

6:,0*i,

f D cartst. ^u,d,ou^tiavr oitr' wc'fuv I'r eJY,Je4.

7"o6 ^( I

4U=