# Determining Solutions for Example Physics Problems

1. How many calories are needed to raise 500 grams of water from 25 degrees Celsius to 40 degrees Celsius?

2. Define the following terms:

a. Internal energy

b. Specific heat

c. Entropy

d. Temperature

3. Suppose a 1 meter long bar expands 0.5 centimeters when heated. By how much will a 100 meter long bar of the same material expand when similarly heated?

4. State how much energy is transferred in each of the following cases:

a. 2 grams of steam at 100 degrees Celsius condenses to water at 100 degrees Celsius.

b. 2 grams of boiling water at 100 degrees Celsius cools to ice water at 0 degrees Celsius.

c. 2 grams of ice water at 0 degrees Celsius freezes to ice at 0 degrees Celsius.

d. 2 grams of steam at 100 degrees Celsius turns to ice at 0 degrees Celsius.

5. State and explain the first and second laws of thermodynamics.

6. Calculate the change in internal energy for each of the following systems:

a. 100 joules of energy is added to a system that does 40 joules of external work.

b. 75 joules of energy is removed from a system that has 50 joules of work done on it.

c. 150 joules of energy is added to a system that has 75 joules of work done on it.

7. Explain why a body of water freezes from the top down rather than from the bottom up.

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#### Solution Summary

This solution assists with the example physics problems.