Study Guide Answer Key

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ANSWER KEY
Density & Buoyancy Test Study Guide
1.
2.
What is Density?
a. Density is the comparison of how much matter there is in a certain amount of space.
What is the formula for density?
a.
3.
4.
5.
6.
7.
D=
𝑴
𝑽
What are the units for density? (List both!)
a. g/cm3 or g/mL
What is the density of water? (Include Units)
a. 1 g/mL
What happens if an object is more dense than water?
a. It sinks
What happens if an object is less dense than water?
a. It floats
Using the Triangle method,
Find the formula for
𝑴
Each of the following
Density =
M
𝑽
Mass = D ● V
Volume =
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
D
V
𝑴
𝑫
What happens to the density of an object if you increase the mass, but its volume stays the same?
a. The density will increase
What happens to the density of an object if you increase the volume, but its mass stays the same?
a. The density will decrease
What is buoyancy?
a. The ability of an object to float
What is the buoyant force?
a. The upward force exerted on objects in fluid
What is the Archemides Principle?
a. The buoyant force acting on an object equals the weight (force of gravity) of the fluid displaced
by the object.
What happens to an object in water if the buoyant force is greater than the force of gravity?
a. It will float
What happens to an object in water if the force of gravity is greater than the buoyant force?
a. It will sink
What happens to an object in water if the buoyant force is equal to the force of gravity?
a. It will have neutral buoyancy…or remain in the middle
Why are there different shapes for boats?
a. Because they are built for different reasons- for example, a pontoon (square shape) is built for
relaxing and a large amount of people while boat shapes are built more for speed
What is the best shape and size for a boat that you want to hold the most amount of passengers?
a. A Large Square
18. What is Surface Tension?
a. Surface of any liquid acts like a thin, elastic film
b. Molecules near the surface are attracted to the rest of the liquid
19. Give 3 examples of surface tension.
a. A bug on water
b. A paperclip on water
c. A droplet of water
d. Drops of water on a penny
e. *Examples may vary*
20. What is Cohesion?
a. The force that holds water molecules together
21. What is Water Pressure?
a. Pressure of water- either on another object or on its own.
i. Water pressure depends on depth and density (water exerts more pressure than
air…it is 1000X more dense than air)
*In addition to using your notes to guide you, think about the labs you completed and the video clips
you watched when answering these questions.
Please see Ms. Sparacino with ANY and all questions that you have BEFORE the test…please do not wait
until last minute to ask me about something- I cannot guarantee I will have enough time to help you
fully understand the concept if you do not ask beforehand. Good Luck! 