Physics with Applications II


For the multiple choice questions click on the correct answer for the solution.

1) A standing wave on a guitar string is described by the equation
y = 3.0 cos(2760t)sin(195x)
with the amplitude measured in mm, t in seconds and x in metres. Determine the displacement of the string when t = 0.28 T seconds and x = 0.04 l metres where T is the period and l is the wavelength

A) 3.0 mm

B) -3.0 mm

C) 1.6 mm

D) 0.14 mm

E) -0.14 mm

2) A student's reading problems are corrected with lenses of power +3.0 diopters to give a corrected near point of 0.25 m. The near point without the glasses is:

A) 1.0 m

B) 0.5 m

C) 2.0 m

D) 1.5 m

E) 2.5 m

3) An object is placed 0.05 m in front of a lens made of glass of index of refraction 1.5. The magnification is found to be 2.5. The radius of curvature of the front (first surface) of the lens is 0.6 m. Determine the radius of curvature of the back surface.

A) -0.14 m

B) +0.38 m

C) -0.71 m

D) +0.04 m

E) -0.38 m

4) Cloud-to-cloud lightning produces thunder which can be heard by observers on the ground below. One particularly brilliant flash produced a thunder clap which reached the ground observer 4.0 seconds after the flash and registered 105 db on an intensity level meter held by the observer. What was the acoustical power produced by this particular lightning flash?

A) 6.1 x 10-2 watts

B) 5.8 x 102 watts

C) 3.4 x 107 watts

D) 7.3 x 105 watts

E) 1.9 x 103 watts

5) A bat is flying directly toward a telephone pole at 25 m/s while emitting a constant frequency acoustical signal at 60 kHz. What echo frequency will the bat hear?

A) 40 kHz

B) 50 kHz

C) 60 kHz

D) 70 kHz

E) 80 kHz

6) A nucleus of 21884 Po decays first by alpha emission and then by beta minus emission. The final nucleus is:

A) 21484 Po

B) 21482 Po

C) 21483 Po

D) 21682 Po

E) 21082 Po

7) A mass of 0.85 kg is attached to the end of a spring and placed on a frictionless horizontal table. The other end of the spring is attached to a wall. When the spring and mass is displaced 0.15 m from rest position and released, the system exhibits simple harmonic motion with a frequency of 6.4 Hz Assuming the spring's mass is negligible, determine the spring constant.

A) 1.98 kg s-2 (or N/m)

B) 1370 kg s-2 (or N/m)

C) 1525 kg s-2 (or N/m)

D) 0.82 kg s-2 (or N/m)

E) 4.6 x 10-2 kg s-2 (or N/m)

8) Which of the following are proper dimensions for intensity?

A) ML3/T

B) M2L2/T

C) L2/T

D) M/T3

E) T2/L

9) A radar technician is testing different reflectors for use on pleasure boats such as small sailboats. One model, a spherical shape of diameter 0.5 m was especially good at reflecting radar waves in all directions. The receiver which the technician used to measure the "echo" has a reception area of 1 square metre and receives a signal which is 1 x 10-10 times the power of the transmitted signal. What is the distance between the reflector and the echo receiver? Assume both the transmitted signal and the echo are radiated uniformly in all directions.

A) 6 m

B) 60 m

C) 600 m

D) 6000 m

E) 60000 m

10) Three acoustical speakers produce sounds of intensity 0.1, 0.3, and 1.2 watts per square metre respectively at a detector placed ten metres away. If all three speakers produce the sounds simultaneously, what is the expected intensity level at the detector?

A) 92 db

B) 320 db

C) 122 db

D) 355 db

E) 68 db

Three resistances (20, 40 and 80 ohm) are connected in parallel and the resulting set is connected in series to a 100 ohm resistance (see diagram). What is the equivalent resistance of this set of resistances?


A) 124 

B) 96 

C) 89 

D) 240 

E) 111 

What is the electrical potential at the point p shown on the diagram below? The value of q1 is 5.0 microcoulombs and the value of q2 is minus 15.0 microcoulombs.


A) -1.6 x 106 V

B) +1.6 x 106 V

C) +0.36 x 106 V

D) 0 V

E) -.36 x 106 V


13) Rays from naturally radioactive materials were initially called

A) Becquerel rays

B) Curie rays

C) X-rays

D) Heisenberg rays

E) Rutherford rays

14) The isotope 21484 Po might have two possible modes of decay. It could decay by alpha emission or by beta(-) emission. The half-life for the alpha decay is 3.1 minutes.

A) Write the reaction for both decay processes and determine, using the data below, if both modes are possible. Find the total kinetic energy of the products.


B) Find the decay constant for alpha decay.


C) A 0.001 µg sample of the Po isotope is prepared by neutron irradiation of some smaller nucleus. How many atoms of Po remain after 2 minutes?


Nuclide  Mass
21484 Po  213.99519 amu
21485 At  213.99631 amu
21082 Pb 209.98413 amu
42 He 4.002603 amu
e 0.000550 amu


15. Find the current in each branch of the circuit below, and find the equivalent resistance of the circuit.


16. An object has a height of 2 cm. Its image is formed by a converging lens on a screen that is 20 cm from the lens. When the lens is moved 10 cm closer to the screen (with the object fixed), another image is formed on the screen. Determine the focal length of the lens and the distance from the screen to the object.


17. A baby's "jolly jumper" consists essentially of a (massless) seat attached to the end of an ideal spring, with the other end of the spring securely fastened to the ceiling. When a 10 kg baby is put into the seat, the spring lengthens by 30 cm. You then pull the jolly jumper down 45 cm below its equilibrium position and release.

A) How fast is the baby travelling as he reaches the equilibrium position?


B) How long after the baby is released does he reach a point 20 cm above the equilibrium position?


Two positive charges QA = 5 mC and QB = 15mC, are separated by a distance of 600 nm. Point P lies on a line that bisects the line joining QA and QB. If the distance from P to O is 400 nm, determine the electric field at P.


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