Define the term momentum. Name the device used to measure atmospheric pressure. State two properties of an ideal gas. What is the principle behind the construction of a simple hydrometer?

Here are the solutions to the questions.

1.

a) Momentum is defined as the product of an object's mass and its velocity. It is a vector quantity, and its direction is the same as the velocity of the object.

$$p = mv$$

b) The device used to measure atmospheric pressure is a barometer.

2.

a) Two properties of an ideal gas are:

• The volume occupied by the gas molecules themselves is negligible compared to the total volume of the gas.
• There are no intermolecular forces of attraction or repulsion between the gas molecules. (Alternatively: Collisions between gas molecules and the container walls are perfectly elastic.)

b) The principle behind the construction of a simple hydrometer is Archimedes' principle (or the principle of floatation). This principle states that a floating object displaces a weight of fluid equal to its own weight. A hydrometer sinks deeper in less dense liquids and floats higher in more dense liquids.