Molecular Physics | Thermodynamics Answers

An air bubble has a volume of 2.5 cm3 when it is released at a depth of 40 m of water. What will be its volume when it reaches the surface of the water? Assume that its temperature is constant and that atmospheric pressure = 10 m of water.

A uniform metre rule of weight 1.0N is pivoted at the 0.40m mark. A 2.0N weight is hung from the 0.15m mark. Where must a 2.0N weight be placed to balance the rule?

The specific heat capacity of ethanol is 2440J/kg °C. How many joules of energy will be required to heat 150g ethanol to 35°C if the starting temperature is 22°C?

If temperature does not change, Boyle’s law can be applied to a gas. Imagine a little container filled with some gas and a moveable piston on top. By pushing the piston down, the gas gets compressed and its pressure increases. The piston’s weight is very small, so by just “sitting” on the gas it does not really do much to it, and the gas maintains normal atmospheric pressure (101,325 Pa) at a volume of about 1 liter (0.001 m3). Let’s say the container’s wall is very thin and can stand an overpressure of max. 151,325 Pa. To what volume in m^3 would you have to compress the gas to make that happen? (Write the number only in the form #x10^(-#) (mind the parantheses and the minus sign in the 10-power), that is, 1 significant figure)

A machine is 12% efficient. If useful work done by the machine is 6 joules then calculate the total amount of heat

A rod of iron and a rod of zinc are each 2 meters long at 0 degree and both are heated equally. At 50 degrees centigrade the Zinc rod is found to be longer by 0.181cm. Find the linear expansivity of iron when that of zinc is 0.0000598 per k.

1. How many joules and kilocalories are generated when the brakes are used to bring a 1300-kg car to rest from a speed of 95 kg/h? (1 cal = 4186 J)

2. An iron boiler of mass 180 kg contains 730 kg of water at 18 *C. A heater supplies energy at the rate of 58,000 kJ/h. How long does it take for the water to:
(a) reach the boiling point,
(b) and all have changed to steam?
(Ciron = 450 J/kg-*C; Cwater = 4186 J/kg-*C; Lv = 2256 kJ/kg)

3. One end of a 56 cm long copper rod with a diameter of 2 cm is kept at 460 *C, and the other is immersed in water 22 *C. Calculate the heat conduction rate along the rod.
(Kcopper = 380 W/m-*C)

A body vibrating with simple harmonic motion has a frequency of 4Hz and an amplitude of 0.15m.
Calculate
1. The maximum values of the acceleration and velocity
2. The acceleration and velocity at a point 0.09m from the equilibrium position of motion

A Zinc rod is measured by means of a brass scale (which is correct at 0 degree) and is found to be 1.0001 metres long at 10 degrees. What is the real length of the rod at 0 degree and at 10 degrees? Mean linear expansivity of the Zinc and is 0.000029 per K and of brass is 0.000019 per K.

A metal tape correct at 30 degrees is used to measure the length of field on a day when the temperature is 20 degrees. How does this affect the result.? What is the error measuring a distance of 10meters? The linear expansivity of the metal is 18x10 raise to power of - 6 per k.