# PHY440 Mechanics, Waves and Thermal Physics

Tags PHY440 Mechanics, Waves and Thermal Physics

Text book: Jewett, J.W. and Serway, R.A. (2010). Physics for Scientists and Engineers with Modern

Physics, 8th Edition, Brooks/Cole Cengage Learning.

Assignment 4

Question / Topic / Problem
1 / Section 14.1 Pressure / No 2 (Softcopy) p.423; No 4 (Hardcopy) p. 423
2. The nucleus of an atom can be modeled as several
protons and neutrons closely packed together. Each particle
has a mass of 1.67 1027kg and radius on the order
of 1015m. (a) Use this model and the data provided to
estimate the density of the nucleus of an atom. (b) Compare
your result with the density of a material such as iron.
What do your result and comparison suggest concerning
the structure of matter?
2 / Section 14.3 Pressure Measurements / No 21 (Softcopy) p.425; No 21 (Hardcopy) p. 425
21. Mercury is poured into a U-tube as shown in Figure
P14.21a. The left arm of the tube has cross-sectional area A1
of 10.0 cm2, and the right arm has a cross-sectional area A2
of 5.00 cm2. One hundred grams of water are then poured
into the right arm as shown in Figure P14.21b. (a) Determine
the length of the water column in the right arm of the
U-tube. (b) Given that the density of mercury is 13.6 g/cm3,
what distance h does the mercury rise in the left arm?

3 / Section 14.4 Buoyant Forces and Archimedes’s Principle / No 22 (Softcopy) p.425; No 26 (Hardcopy) p. 426
22. A light balloon is filled with 400 m3 of helium at atmospheric
pressure. (a) At 0°C, the balloon can lift a payload
of what mass? (b) What If? In Table 14.1, observe that the
density of hydrogen is nearly half the density of helium.
What load can the balloon lift if filled with hydrogen?
4 / Section 14.4 Buoyant Forces and Archimedes’s Principle / No 24 (Softcopy) p.425; No 24 (Hardcopy) p. 425
24. The gravitational force exerted on a solid object is 5.00 N.
When the object is suspended from a spring scale and submerged
in water, the scale reads 3.50 N (Fig. P14.24). Find
the density of the object.

5 / Section 14.6 Bernoulli’s Equation / No 42 (Softcopy) p.427; No 40 (Hardcopy) p. 427
42. Water falls over a dam of height h with a mass flow rate
of R, in units of kilograms per second. (a) Show that the
power available from the water is
P = Rgh
where g is the free-fall acceleration. (b) Each hydroelectric
unit at the Grand Coulee Dam takes in water at a rate of
8.50 105kg/s from a height of 87.0 m. The power developed
by the falling water is converted to electric power
with an efficiency of 85.0%. How much electric power does
each hydroelectric unit produce?
6 / Section 16.3 The Speed of Waves on Strings / No 21 (Softcopy) p.484; No 40 (Hardcopy) p. 427
21. An Ethernet cable is 4.00 m long. The cable has a mass of
0.200 kg. A transverse pulse is produced by plucking one
end of the taut cable. The pulse makes four trips down and
back along the cable in 0.800 s. What is the tension in the
cable?
7 / Section 20.2 Specific Heat and Calorimetry / No 6 (Softcopy) p.592; No 2 (Hardcopy) p. 592
6. The temperature of a silver bar rises by 10.0°C when it
absorbs 1.23 kJ of energy by heat. The mass of the bar is
525 g. Determine the specific heat of silver from these
data.
8 / Section 20.2 Specific Heat and Calorimetry / No 9 (Softcopy) p.593; No 11 (Hardcopy) p. 593
9. A 1.50-kg iron horseshoe initially at 600°C is dropped into
a bucket containing 20.0 kg of water at 25.0°C. What is the
final temperature of the water–horseshoe system? Ignore
the heat capacity of the container and assume a negligible
amount of water boils away.
9 / Section 20.3 Latent Heat / No 16 (Softcopy) p.593; No 20 (Hardcopy) p. 594
16. A 3.00-g lead bullet at 30.0°C is fired at a speed of 240 m/s
into a large block of ice at 0°C, in which it becomes embedded.
What quantity of ice melts?
10 / Section 20.6 Some Applications of the First Law
of Thermodynamics / No 35 (Softcopy) p.595; No 35 (Hardcopy) p. 595
35. An ideal gas initially at Pi, Vi,
and Ti is taken through a cycle
as shown in Figure P20.35.
(a) Find the net work done on
the gas per cycle for 1.00 mol
of gas initially at 0°C. (b) What
is the net energy added by heat
to the gas per cycle?

11 / Section 20.6 Some Applications of the First Law
of Thermodynamics / No 37 (Softcopy) p.595; No 37 (Hardcopy) p. 595
37. A 1.00-kg block of aluminum is warmed at atmospheric
pressure so that its temperature increases from 22.0°C to
40.0°C. Find (a) the work done on the aluminum, (b) the
energy added to it by heat, and (c) the change in its internal
energy.

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