Transcript 100 Kinematics Forces Energy Waves & Sound Electricity

Kinematics
Forces
Energy
Waves &
Sound
100
100
100
100
100
200
200
200
200
200
300
300
300
300
300
400
400
400
400
400
500
500
500
500
500
Electricity &
Magnetism
Kinematics 100
In what region(s) is the object
speeding up?
v
(m/s)
[N]
A
10.5
B
t (s)
2.4
5.0
2.8
-7.3
C
C
Kinematics 200
Calculate the displacement of the
object represented in the v-t graph.
v
(m/s)
[N]
A
10.5
B
t (s)
2.4
5.0
2.8
-7.3
C
10.5(0.4)  7.3(2.3)
d  10.5(2.4) 

2
2
 18.9m[ N ]

Kinematics 300
Find the resultant displacement of the
following displacement vectors.
12m [E], 17m [N20W], 8m [W50S]

d x  12  17 sin 20  8 cos 50  1.04

d y  17 cos 20  8 sin 50  9.85
d R  1.04  9.85  9.90
2
2
  tan 1 (9.85 / 1.04)  84

d R  9.90m[ E84 N ]
Kinematics 400
What direction should you aim your
boat if you hope to paddle directly
across a river which is flowing at
7.5m/s [W] and you are able to
paddle with a speed of 12m/s in still
water? Assume you are standing on
the south side of the river.
12m/s
7.5m/s
cos   7.5 / 12
  51
[ E 51N ]or[ N 39 E ]
Kinematics 500
A model rocket is launched from the
ground with a velocity of
73m/s[E45N]. What is its horizontal
range?
d y  v1 y t 
a y t 2
2
d x d x
t 

v1x
v1 y
a y d x
d x
d y  v1 y

v1 y
2v1 y 2
d y  d x 
a y d x
2
2
2v1 y 2
(9.81)d x
0  d x 
2(73 sin 45) 2
2
0  0.00184d x  d x
2
0  0.00184d x (d x  543.2)
d x  540m[ E ]
Forces 100
An object has a weight of 49.05N on Earth.
What will its weight be on a planet where
g=3.43m/s^2?
Fg  mg
Fg
49.05
m

 5.00kg
g
9.81
Fg 2  mg2  5.00(3.43)  17.2 N
Forces 200
A 10kg object is resting on a flat
surface with static and kinetic
coefficients of friction of 0.35 and
0.20 respectively. If 25N of force
is applied to the object, what will
be the force of friction?
F fs   s FN
F fs   s mg
F fs  0.35(10)(9.81)  34 N
F fs FA  25 N
Forces 300
A 10kg object is resting on a flat surface with
static and kinetic coefficients of friction of 0.35
and 0.20 respectively. If 40N of force is applied
to the object, what will be the force of friction?
F fs   s FN
F fs   s mg
F fs  0.35(10)(9.81)  34 N
FA  F fs
 F f  F fk   k mg  0.2(10)(9.81)  20 N
Forces 400
Determine the maximum mass of the
hanging object for the system to
remain static.
m=10kg
μs=0.500
FgB  F fsA
mB g   s m A g
mB   s m A  0.5(10)  5.0kg
Forces 500
You push a 12kg shopping cart at an
angle of 25 degrees above the
horizontal with an applied force of
35N. The kinetic coefficient of
friction between the wheels and the
ground is 0.10. Determine the
acceleration of the cart.
 Fy  ma y
FN  FAy  Fg  0
FN  35 sin 25  12(9.81)  132.51N
 Fx  max
FAx  F fk  max
FA cos    k FN  max
35 cos 25  (0.1)(132.51)  12a x
m
a x  1.54 2
s
Energy 100
Calculate the thermal energy
released when 0.52kg of Uranium is
completely annihilated via nuclear
fission.
E  mc
2
E  (0.52)(3.00 10 )
8 2
E  4.68 10 J
16
Energy 200
How fast will an object be traveling
after 10.0m if it is dropped from rest,
provided air resistance is neglected?
ET 1  ET 2
E g 1  Ek 2
2
mv
mgh1 
2
v  2 gh1  2(9.81)(10.0)  14.0m / s
Energy 300
Determine the shortest stopping
distance of a 1500 kg car traveling
100km/hr on a horizontal road if the
maximum static coefficient of
friction the tires are able to generate
is 0.75
v1  100km / hr  27.78m / s
Ek 1  W  E K 2
2
mv1
 F f d cos   0
2
2
mv1
  s mgd cos   0
2
2
v1
27.782
d  

 52.4m
2  s g cos 
2(0.75)(9.81) cos(180)
Energy 400
How long, in minutes, will it take a
300W electric kettle which is 92%
efficient to bring 0.50kg of water to
its boiling pt? The specific heat
capacity of water is 4200J/kgC and
is initially at 25C.
Pout

100%
Pin
Pout  0.92(300)  276W
Q  mCT  (0.500)( 4200)(100  25)  157500 J
Q
Pout 
t
Q 157500
t 

 570.65s  9.5 min
Pout
276
Energy 500
Determine the height of the first hill
of a roller coaster with m=40,000kg
if it leaves the first hill from rest and
is traveling at 15m/s at the top of the
second hill which is 17m high. The
average force of friction between the
wheels and the track is 700N and the
length of track between the top of
the first and second hill is 200m.
ET 1  Win  ET 2  Wout
E g1  E g 2  Ek 2  F f d
2
mv
mgh1  mgh2 
 F f d
2
2
F f d
v
h1  h2 

2g
mg
152
700(200)
h1  17 

 29m
2(9.81) 40,000(9.81)
Waves 100
If sound is traveling at 322m/s,
what is the temperature outside?
v  331  0.59T
v  331 322  331
T 

 15.3C
0.59
0.59
Waves 200
The shortest resonance length of
an open air column is 7.5cm
when played with a 1200Hz
sound. Determine the 2nd
resonance length.
Ln  n

2
2 Ln

n
2 L1 2 L2

1
2
L2  2(7.5)  15cm
Waves 300
Two nodes in an electromagnetic
standing wave pattern are 6.1cm
apart. The source emits
2,450,000,000 electromagnetic
waves each second. Determine
the velocity of the wave.
d

2
  2(6.1)  12.2cm  0.122m
f  2450  10 Hz
6
v  f  (2450  10 )(0.122)  2.99  10 m / s
6
8
Waves 400
Determine the temperature in a
room where the shortest
resonance length of a closed air
column exposed to a 720Hz
sound is 12cm.

L1  (2n  1)
4
4 L1
4(12)


 48cm
(2n  1) (2(1)  1)
v  f  720(0.48)  345.6m / s
v  331  0.59T
345.6  331
T
 24.7C
0.59
Waves 500
While watching a storm on a muggy
32C summer day, you record 2 times,
10 seconds apart from one another. The
first time you record is a 5.2s delay
from when you see a flash of lightning
to when you hear the corresponding
thunder. The next time delay you
record is 4.7s. How quickly is the
storm approaching you?
v  331  0.59(32)  349.88m / s
d1  vt1  349.88(5.2)  1819.37 m
d 2  vt 2  349.88(4.7)  1644.43m
1819.37  1644.43
vstorm 
 17.5m / s
10
Electricity & Magnetism 100
A compass is placed below a
straight conductor whose
current is flowing [W]. What
direction will the compass
needle point?
South
Electricity & Magnetism 200
A conductor is placed within a
magnetic field whose field
lines point [S]. If the current
flowing out of the plane that
intersects the magnetic field,
what is the direction of the
force the conductor
experiences?
East
Electricity & Magnetism 300
Two loads of 15ohm and 25ohm
are connected in series to a
battery. If the current flowing
through the first load is
250mA, what is the potential
difference at the battery?
Req  R1  R2  15  25  40
I s  I1  0.25 A
Vs  I s Req  0.25(40)  10V
Electricity & Magnetism 400
Two loads R1=200ohm and
R2=600ohm are connected in
parallel to a battery. The
current leaving the battery is
0.100A. Determine the current
flowing through R2.
1
1
1


Req
R1
R2
Req 
VS
1
 150
1
1

200
600
 I S Req  0.100(150)  15.0V
V2  VS  15.0V
I2
V2
15.0


 0.025 A
R2
600
Electricity & Magnetism 500
A 110V power supply pushes
charge through the combined
circuit as follows:
R1=100ohm, connected in
series, then R2 & R3
connected in parallel with one
another, in series with R1.
I1=0.250A, I2=0.100A.
Determine R3.
V1  I 1R1  0.250(100)  25V
VS  V1  V3
V3  110  25  85V
I1  I 2  I 3
I 3  0.250  0.100  0.150 A
V3
85
R3  
 567
I 3 0.150
The Final Jeopardy Category is…
•Mr. Langlois
(Please write down your wager and
give it to Mr. Langlois)
FINAL Jeopardy
Here’s the answer…
The brand of
bike that
Mr. Langlois
races.
(Give your response in the
form of a question)
What is….