Title: Data Analysis and Presentation

Quiz#1 Solution

Sunday, September 18, 2005 Sec:7

A sinusoidal transverse wave travels along a string. The time for a particle on the string to move from maximum displacement to zero displacement is 0.170 seconds. What is the frequency of the source?

(a) 23.3 Hz

(b) 1.47 Hz

(d) 2.94 Hz

(e) 5.88 Hz

Solution: Displacement

T = 4(0.17)

= 0.68 s

= 1.47 Hz

The solution is (b).

Quiz#1 Solution

Tuesday, September 21, 2005 Sec:8

A string 180 cm long has a fundamental frequency of vibration of 300 Hz. What length of the same string, under the same tension, will have a fundamental frequency of 200 Hz?

(a) 900 cm.

(b) 270 cm.

(d) 147 cm.

(e) 220 cm.

Solution:

For L=180 cm

For the new length:

The speed is the same because tension and linear mass density are the same:

L= 270 cm

The solution is (b).

Quiz#1 Solution

Sunday, September 18, 2005 Sec:9

Ocean waves, with a wavelength of 12 m, are coming in at a rate of 20 crests per minute. What is their speed?

(a) 8.0 m/s

(b) 4.0 m/s

(d) 30 m/s

(e) 16 m/s

Solution:

Frequency =

= 4 m/s

The solution is(b).

Quiz#2 Solution

Sunday, September 25, 2005 Sec:7

When a certain string is clamped at both ends, the lowest four resonant frequencies are 50, 100, 150 and 200 Hz. When the string is also clamped at its midpoint ( without changing the tension), then the lowest four resonant frequencies are

(a) 50, 100, 150 and 200 Hz.

(b) 35, 50 , 75 and 100 Hz.

(d) 50, 150, 250 and 300 Hz.

(e) 100, 200, 300 and 400 Hz.

Solution:

L/2

For length =L

here

For length =

= n(100)

The Solution is (e)

Quiz#2 Solution

Tuesday, September 27, 2005 Sec:8 A sound wave of 50.0 cm wavelength enters the tube shown in figure(1) at the source end. What must be the smallest radius(r) (other than zero) such that a maximum sound will be heard at the detector end?

(a) 15.9 cm.

(b) 21.3 cm.

(d) 17.5 cm.

(e) 43.8 cm.

Solution :

The solution is (e).

Quiz#2 Solution

Sunday, September 25, 2005 Sec:9

A 40 cm string of linear mass density 8.0 g/m is fixed at both ends. The string is driven by a variable frequency audio oscillator ranged from 300 Hz to 800 Hz. It was found that the string is set in oscillation only at the frequencies 440 Hz and 660 Hz. What is the tension in the string?

(a) 125 N.

(b) 496 N.

(d) 322 N.

(e) 248 N.

Solution:

= 660 – 440

= 220 Hz

= 248 Hz

The solution is (e)

fi Quiz#3 Solution

Sunday, October 2, 2005 Sec:7

nal-032-Q02 18-05

Question 1 0.33-72%

A point source emits 30 W of sound. A small microphone has an area of 0.75 cm**2 is placed 10 m from the point source. What power does the microphone receive?

(a) 30 micro-W.

(b) 0.1 micro-W.

(d) 1.8 micro-W.

(e) 3.6 micro-W.

Solution:

The intensity for a point is given by

The solution is (d).

Quiz#3 Solution

Tuesday, October 5, 2005 Sec:8

A pipe is closed at one end and open at the other, and has a length of 0.500 m. The pipe is filled with air. What is the resonant frequency corresponding to the mode shown in figure 5? Use 344 m/s as the speed of sound in air.

(a) 172 Hz

(b) 429 Hz

(d) 515 Hz

(e) 860 Hz

Solution:

For a pipe closed from one end, the harmonic number is given by two number of quarter, there we have 5 quarters waves, thus n=5

The solution is (e).

Quiz#3 Solution

Sunday, October 2, 2005 Sec:9

Question 2 0.19-59%

In figure 1, two speakers, A and B, are driven by the same oscillator at a frequency of 170 Hz and face each other at a distance of 2.0 m. What is the number of minima along the line joining the two sources? [Consider only the nodes between the two sources.] [Take the speed of sound in air = 340 m/s]

(a) 2

(b) 4

(d) 5

(e) zero

Solution:

0.5m

At the middle we have antinode.

Number of nodes where you have minimum intensity is 2.

The solution is(a).

fQuiz#4 Solution

Sunday, October 9, 2005 Sec: 7

The wall of a home is 0.2m thick, 0.2m high, 10 m wide and has a thermal conductivity of 0.4 watt/m/K. If the inside temperature is 15 degrees Celsius and the outside temperature is -5.0 degrees Celsius, how much energy is lost in 12 hours?

(a) 4.5*10**6 J.

(b) 4.5*10**5 J.

(d) 2.7*10**7 J.

(e) 3.4*10**7 J.

Solution:

The solution is(e).

fQuiz#4 Solution

Sunday, October 11, 2005 Sec: 8

A cylinder with a frictionless piston contains 0.2 Kg of water at 100 degrees Celsius. What is the change in internal energy of water when it is converted to steam at 100 degrees Celsius at constant pressure of 1 atm.[Density of steam =0.6Kg/m**3, water =10**3Kg/m**3]

Heat of vaporization for water is 2256 kJ/kg. 1atm = 1.01 X 10**5 Pa.

(a) 418kJ

(b) 452kJ

(d) 113 kJ

(e) 333 kJ

Solution:

The solution is(a).

fQuiz#4 Solution

Sunday, October 9, 2005 Sec: 9

One kilogram of water id initially at a temperature of 30.0 degrees-C. How much ice, initially at a temperature of zero degrees-C, must be added to the water to make a mixture whose equilibrium temperature is 10.0 degrees-C?[ The specific heat of water is 4190J/kg.K and the heat of fusion is 333kJ/kg.]

(a) 252g

(b) 224g

(d) 200g

(e) 476g

Solution:

The solution is(b).

Quiz#5 Solution

Sunday, October 23, 2005 Sec:7

A charge of +3.2*10**(-6) C is placed at the origin. A second charge (q2) is placed at x =3.0m. If a charge of 1.0*10**(-6) C experiences no force if placed at x=4.0 m , then q2 is :

(a) +0.2*10**(-6) C.

(b) -3.3*10**(-6) C.

(d) +0.2*10**(-6) C.

(e) -2.1*10**(-6) C.

Solution:

q1=+3.2*10**-6 q2 F32 q3=1.0*10**-6

F31

3.0 m r32=1m

r31=4.0 m

The charge of q2 should be negative, since the force on q3 due to q2 should point to

the left.

The solution is (c).

Quiz#5 Solution

Sunday, October 25, 2005 Sec:8

In figure 3, Q = 60 micro-C, a = 3.0 m, and b = 4.0 m. Calculate the total electric force on q. [I and j are the unit vectors in the positive directions of x-axis and y-axis, respectively].

q X

(a) 1.12j(N)

(b) -0.34 I (N)

(d) 0.34 I (N)

(e) 0.69 I (N)

Solution:

a B

q X

Along y-axis Fy = 0

Along X-axis Since

Quiz#5 Solution

Sunday, October 23, 2005 Sec:9

Charges q1 and q2 are on the x-axis. q1 is at x = a and q2 is at x = 2a. The net force on a third charge at the origin is zero. Which of the following is TRUE?

(a) q2 = -4*q1

(b) q2 = 2*q1

(d) q2 = -q1

(e) q2 = -2*q1

Solution:

q3 q1 q2

a 2a

The sign of q2 should be opposite of that of q1 since their forces on q3 should point in opposite directions.

The Solution is(c)

Quiz#6 Solution

Sunday, November 13, 2005 Sec:7

Vi = 50

Quiz#6 Solution

Sunday, November 15, 2005 Sec:8

Total flux = 0

Flux through Ф1 cone

Ф2 flux through the base

Quiz#6 Solution

Sunday, November 13, 2005 Sec:9

A proton is shot out along the +x-axis from the origin with a speed of 1.0*10**6 m/s. In this region a uniform electric field of 2500 N/C exits in the negative x-direction. Find the distance traveled by the proton before it momentarily comes to rest.

(a) 8.9 m

(b) 1.0 m

(d) 2.1 m

(e) 2.9 m

E = 2500 N/C

p Vi = 1.0*10**6 m/s

Charge of the proton =

Mass of the proton

= 1.7*10**-27

Quiz#7 Solution

Sunday, Nov.20, 2005 Sec:7

For the two infinite dielectric sheets, see figure(5), find the magnitude of the electric field at a point P. consider that each sheet has a positive surface charge density of 10**2 C/m**2

0.5 m

1.0 m P

(a) 2.2*10**13 N/C

(b) 0.5*10**13 N/C

(d) Zero

(e) 1.7*10**13 N/C

Solution:

but

The solution is (c).

Quiz#7 Solution

Tuesday, Nov 22, 2005 Sec:8

A nonconducting shell has a uniform negative charge of magnitude 5.0*10**(-5) C. Its inner and outer radii are 5.0 cm and 6.0 cm, respectively. The electric field at r = 3.0 cm, from the center, is:

(a) 4.5*10**9 N/C, inward.

(b) 1.5*10**9 N/C, outward.

(d) 1.5*10**9 N/C, inward.

(e) Zero.

Solution: Total charge 5*10**5 C

6cm

3 cm

5cm

E at 3 = zero.

The solution is (e).

Quiz#7 Solution

Sunday, Nov. 20, 2005 Sec:9

Figure 4 shows cross-section through two large, parallel non-conducting sheets with identical distributions of negative charge. The surface charge density for each sheet is 7.00*10**(-15) C/m**2. What is the electric field at point A?

(a) 7.91*10**(-4) N/C upward.

(b) 3.96*10**(-4) N/C downward.

(d) 7.91*10**(-4) N/C downward.

(e) 0

Solution:

E1 E2

Downward

The solution is(d).

Quiz#8 Solution

Sunday, Nov. 27, 2005 Sec:7

nal-032-Q02 18-05

Question 1 0.33-72%

Two large, parallel, conducting plates are 20 cm apart and have charges of equal magnitude but opposite signs on their facing surfaces. An electron, placed anywhere between the two plates experience an electrostatic force of 1.6*10**(-15)N. Find the magnitude of the potential difference between the two plates.

(a) 30 kV.

(b) 50 kV.

(d) 10 kV.

(e) 4 kV.

Solution:

20 cm plate plate

Uniform electric field:

=2 kV

The solution is (c).

Quiz#8 Solution

Tuesday, Nov. 29, 2005 Sec:8

Question 2 0.54-65%

Over a certain region of space, the electric potential is give by: V(x,y) = x**2+y**2+2*x*y. find the angle that the electric field vector makes with Z-axis at point(1.0,2.0,0.0).

(a) 75 degrees

(b) 45 degrees

(d) 0 degrees

(e) 60 degrees

Solution:

Electric field is in x-y plane:

Quiz#8 Solution

Sunday, Nov 27, 2005 Sec:9

Question 3 0.19-59%

An infinite nonconducting sheet has a surface charge density 0.10*10**(-6) C/m**2 on one side. How far apart are equipotential surfaces whose potentials differ by 90 V.

(a) 2.0 cm.

(b) 1.6 cm.

(d) 1.8 cm.

(e) 2.5 cm.

Solution:

Uniform electric field:

The solution is (c).

Quiz#9 Solution

Sunday, Dec 4, 2005 Sec:7

Question 3 0.19-59%

If Vab is equal to 50 V, find the charge sloted and the potential difference across the 25 nicro-F capacitor shown in Figure 5.

(a) 600 micro-C and 10V.

(b) 250 micro-C and 40V.

(d) 600 micro-C and 20V.

(e) 250 micro-C and 10V.

Solution:

C12 60 μF

C3 15 μF

q = 600 μC

C123 12 μF

Charges on C12 = Charges on C123

= 600 μC

Voltages on C12 =

Charges on the 25 μF is (10V)(25 μF) = 250 μC

The solution is (e).

Quiz#9 Solution

Sunday, Dec 6, 2005 Sec:8

Question 3 0.19-59%

A certain air filled parallel-plate capacitor is connected across a 20 V battery. When the battery is disconnected and a dielectric slab is inserted into and fills the region between the plates, the voltage across the plates drops by 12 V. What is the dielectric connect of the slab?

(a) 2.5

(b) 1.7

(d) 2.1

(e) 0.6

Solution:

V = 20 v

Air qi

V = 12 v

Since between is

Not connected

The solution is(b).

Quiz#9 Solution

Sunday, Dec 4, 2005 Sec:9

Question 3 0.19-59%

A parallel plate capacitor has a plate area of 0.2m**2 and a plate separation of 0.1 mm. the charge on each plate is 4.0 microCoulombs. What is the electric field between the plates?

(a) 1.0*10**6 V/m

(b) 4.0*10**12 V/m

(d) 4.0*10**2 V/m

(e) zero

Solution:

The solution is(c).