**PHYS*1130**

**Physics with Applications II**

**SAMPLE FINAL EXAMINATION 1**

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 10^{2} watts

C) 3.4 x 10^{7} watts

D) 7.3 x 10^{5} watts

E) 1.9 x 10^{3} 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 ^{218}_{84 }Po decays first by
alpha
emission and then by beta minus emission. The final nucleus is:

A) ^{214}_{84 }Po

B) ^{214}_{82 }Po

C) ^{214}_{83 }Po

D) ^{216}_{82 }Po

E) ^{210}_{82 }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) ML^{3}/T

B) M^{2}L^{2}/T

C) L^{2}/T

D) M/T^{3}

E) T^{2}/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

11)

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

12)

What is the electrical potential at the point p shown on the
diagram
below? The value of q_{1} is 5.0 microcoulombs and the value of
q_{2} is minus 15.0 microcoulombs. |

A) -1.6 x 10^{6} V

B) +1.6 x 10^{6} V

C) +0.36 x 10^{6} V

D) 0 V

E) -.36 x 10^{6} V

**BONUS QUESTION**

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 ^{214}_{84 }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?

DATA:

Nuclide |
Mass |

^{214}_{84 }Po |
213.99519 amu |

^{214}_{85 }At |
213.99631 amu |

^{210}_{82 }Pb |
209.98413 amu |

^{4}_{2} 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?

18.

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