Spring 2019
PH 2217
Principles of Physics I
EXAN4-1
You can use calculator but you are not allowed to use celI phone as your calculator,
question l-72 are multiple choice (12 points each) use "Apperson datalink " for this part (no need
to show work) ,
13-14 are free response questions (15 points each) , show ail steps
show all steps : mysterious answers will receive no credit (no partial credit)
you could use back of the page if extra space is needed
The total points available to attempt is 774 (to help your score) , However the maximum points
you can get (150),
(i.e. If you score 7611174: your score is 150 . If you score 1201774 your score is 120)
No Partial points
Do not forget to write your on name and section for both free response, and multiple choice (10
points wiil be deducted for not writing sections, If you forget to write your name , your exam will
not be graded)
Recitation X4 : B am : section 51
Recitation M : 2:30 pm : section 52
Recitation W : B am : section 59
Recitation W : 11:15 am : section 53
Recitation F : B am : section 60
Recitation F : 11:15 am : section 54
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1. Find the dimension of gravitational constant (G), where F:G(mi.*r)l r' , where rfLlrTfl2
are the masses of two objects, I': force due to gravity, r: distance betr,veen the objects
-4
.1
g,
(r2
(72
A,t',)
(d)
none
of
A,t)
(o
L2
Ut1
L3
them
L,
-34
i
32
6
-t,j
I
k)
I
I
ffi
=
=
e
tnJttlo
* 62
I
2.Addine vectors , -i.:Zi -Si - k and E: -t+2) - 3[ : fi.nd 1e,4-ZE1 3 Ot -rgj t3L
@) ai_ iaj*1e[ (b)B; -ttj +o,t 1c) si-roi-o[ 1a;s? - 26j+1ek S none of them v{zl = o -/g
r 3. A car is traveling in straight line rvith ve1ocit1. 100 m/s . After seeing a deer on the road, v(o) - 'oo-/s
the driver pressed the brake. The break caused a constant deceleration (20 mlsz). What x(o) = o m
* distance will the car travei after pressing the break, before it comes to a complete halt? >< (4t = ) tn
(a) 500* (b) 100m@ 250m (d) noneof them
vft)= ,<o) -ae ? e=teo-)dc a '--2on/t,
x&): x(ol lw(qi -/a< z e -- 55
o 4. Which statements are true ?
< d + /aar/5 - /,rZo*7L, eSOt
(1) Neu'tons 2nd law can only be applied in an inertial frame ( which has no acceleration)
(assume velocity is much less than c ,where c is the velocity of light )
,.
-7
$.{t
r)
(2) speed is a vectory Pccdt's ,.a/d/
(3) If you throw a stone straight up (free fa11) : at the highest point the net force acting
t
\+
it zero
t
^
(4) mass and weight of an object is same physical quantity ^ / n&
(a) 1 and 3 (b) 2, and 3 @only 1 (d) only 4 (e) none of the oF*iaz'r€ dte
It
5 . position vector :
g
$\*$ F. 6.
a
f"\
$.i{tl
N
s {
tzi
- ti
F:
mls2 1a1pi
tst
-
-
--
Yy
=a
Fv/a
m , what is the instantaneous acceleration at time t:2 s
ai mls2 (c) B mls2 1a1 zai + 4j ml s2 (e) none of tgem
; a(e) = € c?- rr?, ac"> =lz?-n?),*\**=8r"
i&t = ?12? -+t?
suppose you throw a ball straight r-rp , and it took 10 s to come back to yo-uf hand (total
time bail was in air: time to go up * time to come down) can you estimate what was the
magnitude of the initial velocity at which you threw the ballup?(no air drag force is present)
(a) 9.8 m/s (b) 10 m/s (c) 98 -/. (S 49 mf s (e) none of them
L_.,
NS
(b)
(a)
@
= Ldo*a
3"@=Ios
E
v(o)
vy+
,nVY
b
t
t,
t
t
up,
represent u, velocity compo-
\ \m
$t
N
zzph;rrt
coalcc+
- 2*j
c 7. A particle is thrown straight up from ground . Which graph
nent versus time . ( Up direction is *y direction)
{y
,ly
vy +
t \d
on !.= c?7?g*
alr"rizzg *tcz
(d)
o B. A10 kg mass is attached to the ceiling of an elevator by a massless rope. What is the
tension (magnitude) in the rope when the elevator is accelerating downward at 5 m
(a) 98 N (b) 148 N @ 48 N (d) 0 N (e) none of them
v\
ili
T
o
s
rl
s
+
)
tug-T - wa
*(q
- a)
fi
q8N
vvt0
2
/qt
,
Fl*l
+vc
=a?n[
t*
1
+vc
t
{
tf) 's*
$a
.A
r
rt.l
.i. F Iq
\+
!t
ET
tr
Fs {+
o 9. Three forces are acting on an object of mass
net force on the the object :
@, -ls.Ti + 6.34iN (b) -17.3;
l+ ng;nlo'l
7.+o"osgoo
in figure below . Find out the
- 6.24j N (c) -1.37? +a.s+i N (d) none of them
+, f
r44
4-+D- *c
I
eor
8, - eocosro' | + eosi?rgo.-f
? = - n Stov;f - ro cer So' f
10 kg as shown
I
I
a00
toN
'&i,
A
n*
=
'a
- tgt'? i + 6'7tj
c
,ON
o 10. An object of mass (m) is pulled upa by a rope on an incline plane. The tension force
T acting on rope is paralle1 to the incline plane, and a is the acceleration of the object up
the plane . Incline plane makes an angei 6 with horizontal , and assume there is no friction
present. Which one below are the correct set of Newton's second lar,vs along x and y
force
$ h
s
t
directions
+
{
Sr
r{I
$
t\
.$
$ ${
*
4
s
t|'
*\\
\
I
:
a
xt')
$
a- Yn€in| , wta z
N-m ca9O -- o
I
oz
ateng 5 a.c c
"Urafz
,nt
o
: ma, N - mg (b) T- mg cos0 : 0, N -mgsind : ma
ffi) T--g sind : ma, N-mg cosd : 0 (d) T - mg, N- mgcos I :0
(a)T
(e) none of them
o 11.A person is standing at the
edge of the cliff (c1iff is 100 m high from sea) If the person
throws a stone 10 m/s straight up , what r,viIl be the velocity when it hits the sea?
+
i)
ef
@) -t}mls (b) -65.37 m/s (c) -75.37 -/. ffi) none of them
+ lOtulg
,n+ve
(aro 2
I
f (ot = a ,/,
Y&S =''oo4z
v7a) = ta ,?r/g
A 3 - g.gm/jz
r(cl= -/oa = o*tat-?Qczg
rz (c)
/o
= La .g ,r 5.6i * ,rF,r?m/, e = ,.69
l60n
s
o 72. A 5 kg mass hangs from a massless rope . A force 20 N is applied horizontally on the
mass. ff the net force on the mass is zero . Find out the tension force on the rcipe
:
(a) 49 N (b) 68.48 N ffif 52.92 N (d) none of
them
I
4,
zON .- -. *r.
o
I
t
I
s
loN
vna
'T=
20
sin I
2
52'.O2
hro
N
=
.20
ta9
0* za.2o
<F
Tcog6=
tu7 €
Tginp=26 €
r)
D
'Tca90-w$=o -1(t)
2a- rsiu7=o ->(zt
Hut
-2
7p
p
dlga Ao12-Z aDEIT|ON
t0tule
NAMtr
:
+
SECTION:
/+a bt
circle your flnal answers with proper units :
no points will be awarded if don't show steps and write expression/result directly :
(13) A rock of mass 2 Kg is thrown horizontally direction from the roof of a building with an
initial velocity of 10 m/s t. fn" rock hits the ground 140 m from the base of the building
How long will it take to hit the ground ( 4+1 pts)
.
dz= /+ari
y'z
= ,/o
v2
/qD
t
* lsrtp#Nptq f do'a f
What is the height of the building 7 ( 4
Y(€)=
,
what is the Vo
;j o
=)+s
/a
+
4"b$e
^o
(tu)z
t
1 pts)
f,'r r/6- -7?r-:
d 0.fl
dr*
uN,T
/+
H=
uN' -r
):/t
(l r'.''1;
=
: y component of the velocity
when
it
is about to hit the ground
?
(4+1
pts)
Vy({) s o +A*
)'$ x tg
#Y
r*#,A
4
to) * €)
&r
f
,s
Vv!
uNtT
r:...'i
i
Pfrl*
Don€ auaing taalut2 1 9)125
Ftavm evt?-3
circle your final answers with proper units :
no points will be awarded if don't show steps and write expression/result directly :
(14) 5 kg box starts from rest and slides down an incline of an 30' incline (angle incline plane
makes with horizontal) . The coefficient of friction betu,een the box and the incline is #x:0.1
\-
/o,?,
rr
&
lv\8
*7
Find out the normal force (4+1 pts)
*
*g
m3
Foa €lidiug t?'ais
AJ
,$
i;4,: i-, l-:". -'
lrl =
+ Nz
1.,
*2, ?b
Find out the acceleration down the incline? (4+1 pts)
ax
&*x
;l-t* mlcai #
m$#*ao-s E fi4
4 s rr!|bifl & * /l{lh?(.a$s
4r,
uNrT
8a 3l*b
tn ff 5E#
g * g,gm/5L
r"t0c6##
tu +2,+fi N
S,
A/
*'*6
UN
t,
:
#6 wl* tu
bYt
If the incline is 10 m long . How long will it take to
xf,{.J
r
s *o*n
-
(
g,
-.-
S It/d?
,f*
&
k2
? (4+1 pts)
t
n x&)
d
reach the bottom
.,d5d!#
=
+'o
"$
5
r
,r
'gg
uNrT