Forces, Motion, and Energy Ch 3 Review

In each of the next 5 sentences, replace the incorrect term with the correct term for the following words. THRUST, DRAG, BUOYANT FORCE, PASCAL'S PRINCIPLE, BERNOULLI'S PRINCIPLE, PRESSURE, LIFT, FLUID


Lift increases with the depth of a fluid.

Replace lift with pressure

A plane's engines produce drag to push the plane forward.

Replace drag with thrust

A pascal can be a liquid or a gas.

Replace pascal with fluid

A hydraulic device uses Archimedes' principle to lift or move objects.

Replace Archimedes' principle with Pascal's principle

Atmospheric pressure is the upward force exerted on objects by fluids.

Replace Atmospheric pressure with Buoyant force

The design of a wing...
A) causes the air above the wing to travel faster than the air below the wing.
B) helps create lift.
C) creates a low-pressure zone above the wing.
D) All the above

D) All the above

Fluid pressure is always directed...
A) up
B) down
C) sideways
D) in all directions

D) in all directions

An object surrounded by a fluid will displace a volume of fluid that is
A) equal to its own volume
B) less than its own volume
C) greater than its own volume
D) denser than itself

A) equal to its own volume.

If an object weighing 50N displaces a volume of water that weighs 10N what is the buoyant force on the object? A) 60N B) 50N C)40N D) 10N

D) 10N

A helium-filled balloon will float in the air because... A) there is more air than helium
B) helium is less dense than air
C) helium is as dense as air
D) helium is more dense than air

B) helium is less dense then air

Materials that can flow to fit their containers include
A) gases
B) liquids
C) both gases and liquids
D) gases, liquids, and solids

C) both gases and liquids

Where is water pressure greater, at a depth of 1 m in a large lake or at a depth of 2 m in a small pond? Explain

Water pressure is greater at a depth of 2 m in a small pond. Pressure increases with depth regardless of the amount of fluid present.

Why are bubbles round?

Bubbles are round because air, like all fluids, exerts pressure evenly in all directions. So, when you blow a bubble, the bubble expands in all directions to create a sphere.

Why are tornadoes like giant vacuum cleaners?

Tornadoes are like giant vacuum cleaners because the air rushing into the tornado pushes objects into a tornado. This process is similar to the way dirt is pushed into a vacuum cleaner.

Forming Hypotheses: Gases can be easily compressed into smaller spaces. Why would this property of gases make gases less useful than liquids in hydraulic brakes?

If a gas were used in hydraulic brakes, the brakes would not work. When the brake pedal is pushed, the gas wold compress and therefore would not push on the brake pads to stop the wheels.

Making Comparisons: Will a ship loaded with beach balls float higher or lower in the water than an empty ship? Explain your reasoning.

The ship will float lower in the water because the beach balls will add to the total mass of the ship but will not increase the volume. Therefore, the overall density of the ship will increase, causing the ship to sink a little.

Applying Concepts: inside all vacuum cleaners is a high-speed fan. Explain how this fan causes the vacuum cleaner to pick up dirt.

The fan causes the air inside the vacuum cleaner to move faster, which decreases pressure. The higher air pressure outside of the vacuum then pushes dirt into the vacuum cleaner.

Evaluating Hypotheses: A 600 N girl on stilts says to two 600 N boys sitting on the ground, "I am exerting over twice as much pressure as the two of you are exerting together!" Could this statement be true? Explain your reasoning.

Yes, the statement could be true. Pressure is equal to force divided by area. The girl on stilts is exerting force over a much smaller area than the two boys on the ground are. Therefore, it is possible that the girl is exerting twice as much pressure as