Unit Test Review

What is the SI unit of pressure?

• Atmosphere

• Pascal

• Newton

• Joule

Answer explanation

The SI unit of pressure is the Pascal (Pa), defined as one newton per square meter. While atmosphere, newton, and joule are related to pressure, only Pascal is the standard unit in the International System of Units.

Which of the following is a fluid?

• Wood

• Water

• Rock

• Metal

Answer explanation

Water is a fluid because it can flow and take the shape of its container. In contrast, wood, rock, and metal are solid materials that do not flow.

How is pressure calculated?

• Force + Area

• Force - Area

• Force × Area

• Force ÷ Area

Answer explanation

Pressure is calculated using the formula: Pressure = Force ÷ Area. This means that pressure is the amount of force applied per unit area, making 'Force ÷ Area' the correct choice.

What causes pressure in a fluid?

• The shape of the container

• The weight of the fluid

• The temperature of the fluid

• The movement of the fluid

Answer explanation

Pressure in a fluid is primarily caused by the weight of the fluid above a given point. As the weight increases, it exerts more force on the fluid below, leading to higher pressure. Thus, the correct answer is the weight of the fluid.

What happens to air pressure as altitude increases?

• It increases

• It decreases

• It remains the same

• It fluctuates

Answer explanation

As altitude increases, the amount of air above decreases, leading to lower air pressure. Therefore, air pressure decreases with increasing altitude.

Which statement about fluid pressure is true?

• Pressure decreases with depth

• Pressure is exerted only downward

• Pressure is constant at a given depth

• Liquids do not exert pressure

Answer explanation

At a given depth in a fluid, pressure is constant and acts equally in all directions. This means that while pressure increases with depth, it remains uniform at any specific depth, making the correct statement true.

Why are theater seats more comfortable than bicycle seats?

• They are bigger

• They exert pressure over a larger area

• They are softer

• They are more stylish

Answer explanation

Theater seats are designed to distribute weight over a larger area, reducing pressure points, which makes them more comfortable than bicycle seats that concentrate pressure on a smaller area.

How does water pressure change with depth?

• It remains constant

• It decreases

• It increases

• It fluctuates randomly

Answer explanation

Water pressure increases with depth due to the weight of the water above. As you go deeper, there is more water pressing down, leading to higher pressure. Therefore, the correct answer is that water pressure increases.

Why do mountain climbers need oxygen at high altitudes?

• The air is too cold

• The pressure decreases with altitude

• They need to breathe less air

• The atmosphere is too thick

Answer explanation

Mountain climbers need oxygen at high altitudes because the pressure decreases with altitude, leading to lower oxygen levels in the air. This makes it harder to breathe and obtain sufficient oxygen for their bodies.

What happens to a can when it cools after being heated with water inside?

• It stays the same

• It expands

• It gets crushed

• It pops open

Answer explanation

When a can with heated water cools, the steam inside condenses, creating a vacuum. This pressure difference causes the can to get crushed as the external air pressure exceeds the internal pressure.

Tags

NGSS.MS-PS1-4