A 1.0-cm-diameter pipe widens to 2.0 cm, then narrows to 0.5 cm. Liquid flows through the first segment at a speed of 4.0m/s. Part A What is the speed in the second segment? Express your answer using two significant figures. Part B What is the speed in the third segment? Express your answer using two […]

## Problem 13.32

Water flowing through a 2.7-cm-diameter pipe can fill a 100 L bathtub in 6.3 min. Part A What is the speed of the water in the pipe? Express your answer using two significant figures.

## Conceptual Question 13.22

The water of the Dead Sea is extremely salty, which gives it a very high density of 1240 kg/m3. Part A Explain why a person floats much higher in the Dead Sea than in ordinary water as shown in (Figure 1) . Drag the terms on the left to the appropriate blanks on the right […]

## Conceptual Question 13.6

To explore the bottom of a 10 m deep lake, your friend Tom proposes to get a long garden hose, put one end on land and the other in his mouth for breathing underwater, and descend into the depths. Susan, who overhears the conversation, reacts with horror and warns Tom that he will not be […]

## Problem 11.16

The planet Mercury’s surface temperature varies from 700 K during the day to 90 K at night. Part A What is the temperature in ∘C during the day? Express your answer using three significant figures. Part B What is the temperature in ∘C at night? Express your answer using three significant figures. Part C What […]

## Problem 11.22

13 J of heat are removed from a gas sample while it is being compressed by a piston that does 25 J of work. Part A What is the change in the thermal energy of the gas? Express your answer using two significant figures. Part B How does the temperature of the gas change? Increases […]

## Problem 11.13

A weightlifter curls a 26 kg bar, raising it each time a distance of 0.70 m . Part A How many times must he repeat this exercise to burn off the energy in one slice of pizza? Assume 25% efficiency. Energy content of one slice of pizza is 1260 kJ. Express your answer using two […]

## Problem 11.12

The label on a candy bar says 430 Calories. Part A Assuming a typical efficiency for energy use by the body, if a 59 kg person were to use the energy in this candy bar to climb stairs, how high could she go? Express your answer using two significant figures.

## Problem 11.4

An individual white LED (light-emitting diode) has an efficiency of 20% and uses 1.0 W of electric power. Part A How many LEDs must be combined into one light source to give a total of 1.6 W of visible-light output (comparable to the light output of a 40 W incandescent bulb)? Express your answer as […]

## Multiple Choice Question 11.34

While keeping your food cold, your refrigerator transfers energy from the inside to the surroundings. Thus thermal energy goes from a colder object to a warmer one. Part A What can you say about this? It is a violation of the second law of thermodynamics. It is not a violation of the second law of […]

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