91Ó°ÊÓ

Give an example of a physical property that varies with temperature and describe how it is used to measure temperature.

A cleaner pushes a 4.50-kg laundry cart in such a way that the net external force on it is \(60.0 \mathrm{N}\). Calculate the magnitude of its acceleration.

Since astronauts in orbit are apparently weightless, a clever method of measuring their masses is needed to monitor their mass gains or losses to adjust diets. One way to do this is to exert a known force on an astronaut and measure the acceleration produced. Suppose a net external force of 50.0 \(\mathrm{N}\) is exerted and the astronaut's acceleration is measured to be \(0.893 \mathrm{m} / \mathrm{s}^{2} .\) (a) Calculate her mass. (b) By exerting a force on the astronaut, the vehicle in which they orbit experiences an equal and opposite force. Discuss how this would affect the measurement of the astronaut's acceleration. Propose a method in which recoil of the vehicle is avoided.

Why does condensation form most rapidly on the coldest object in a room-for example, on a glass of ice water?

When a cold alcohol thermometer is placed in a hot liquid, the column of alcohol goes down slightly before going up. Explain why.

Why does rubbing alcohol evaporate much more rapidly than water at STP (standard temperature and pressure)?

Under what circumstances would you expect a gas to behave significantly differently than predicted by the ideal gas law?

Dry air is \(78.1 \%\) nitrogen. What is the partial pressure of nitrogen when the atmospheric pressure is \(1.01 \times 10^{5} \mathrm{~N} / \mathrm{m}^{2} ?\)

A constant-volume gas thermometer contains a fixed amount of gas. What property of the gas is measured to indicate its temperature?

The same rocket sled drawn in Figure 4.30 is decelerated at a rate of \(196 \mathrm{m} / \mathrm{s}^{2}\). What force is necessary to produce this deceleration? Assume that the rockets are off. The mass of the system is \(2100 \mathrm{kg}\).