#1. A bargain hunter purchases a "gold" crown at a flea market. After she gets home, she hangs it from a scale and finds its weight to be 7.84 N. She then weights the crown while it is immersed in water, and now the scale reads 6.86 N. Is the crown made of pure gold? (the density of gold is 19300 kg/m3)
#2. An aneurysm is an abnormal enlargement of a blood vessel such as the aorta. Suppose that , because of an aneurysm, the cross-sectional area A1 of the aorta increases to a value of A2 = 1.7A1. The speed of the blood (r = 1060 kg/m3) through a normal portion of the aorta is v1 = 0.40 m/s. Assuming that their aorta is horizontal (the person is lying down), determine the amount by which the pressure P2 in the enlarged region exceeds the pressure P1 in the normal region.
#3. What mass of steam that is initially at 130oC is
needed to warm 200g of water in a 100g glass container from
20.0oC to 50.0oC? (cglass = .200
cal/goC)
#4. If the translational rms speed of the water vapor molecules
(H2O) in air is 648 m/s, what is the translational rms
speed of the carbon dioxide molecules (CO2) in the same
air? Both gases are at the same temperature.
#5. Mercury is poured into a tall glass. Ethyl alcohol is then poured
on top of the mercury until the height of the ethyl alcohol itself is
110 cm. The two fluids do not mix, and the air pressure at the top of
the ethyl alcohol is one atmosphere. What is the absolute pressure at
a point that is 7.10 cm below the ethyl alcohol - mercury interface?
(rethyl = 806 kg/m3, rHg = 13,600
kg/m3)
#6. A grandfather clock is controlled by a swinging brass pendulum that is 1.3000 m long at a temperature of 20.0oC.
a) What is the length of the pendulum rod when the temperature drops to 0.0oC?
b) If this is a simple pendulum, does the change in length of the rod cause the clock to run fast or slow? Explain.
#7. A tank contains 11.0 g of chlorine gas (Cl2) at a temperature of 82oC and a pressure of 5.60 x 105 Pa. a) Determine the volume of the tank. b) Later, the temperature of the tank has dropped to 31oC and, due to a leak, the pressure has dropped to 3.80 x 105 Pa. How many grams of chlorine have leaked out of the tank? The atomic mass of chlorine is 35.453u.
#8. A system gains 1500 J of heat, while the internal energy of the system increases by 4500 J and the volume decreases by 0.010 m3. Assume the pressure is constant and find its value.
#9. Five thousand joules of heat is put into a Carnot engine whose hot and cold reservoirs have temperatures of 500 K and 200 K, respectively. How much heat is converted into work?
Answers:
1. 8000 kg/m3, No
2. 54 Pa
3. 10.9 g
4. 414 m/s
5. 1.19 x 105 Pa
6. a. 1.2995 m, b. clock runs fast
7. a. 8.17 x 10-4 m3, b. 2.3 g
8. 3.0 x 105 Pa
9. 3000 J