MIDYEAR REVIEW

Which of the following can break solid rock?

• Growth of plant roots but not movement of glaciers

• Movement of glaciers but not growth of plant roots

• Both growth of plant roots and movement of glaciers

• Neither growth of plant roots nor movement of glaciers can break solid rock

Answer explanation

The growth of plant roots and movement of glaciers are both types of mechanical, aka physical weathering, since they break down rocks through physical processes.

Rafael lives near a road at the bottom of a hill. His parents are concerned that soil will wash off the hill and rocks will fall onto the road. Rafael conducts an investigation to find out if grass growing on a hillside will help stop soil erosion.

 

He collects two samples of the same size and type of soil. One sample of soil has grass growing on it and the other does not. He places each sample of soil in a small tray. For his investigation, Rafael pours the same amount of water onto both samples of soil. He uses a large tray to collect water that may flow through the soil.

 Which practice shows the best way for Rafael to set up this investigation?

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Answer explanation

In this experiment, the independent variable (aka manipulated variable), is whether the soil has grass or not since Rafael wants to test whether the grass will prevent soil erosion.

Remember you may only have one independent variable in your experiment. The rest (controlled variables) must stay the same.

Tags

NGSS.MS-LS2-3

Each spring, a crevice in the cliff wall widens and deepens.

What is the best explanation for how physical weathering causes the crevice to widen and deepen?

• Winds deposit sand into the crevice.

• Water freezes and expands in the crevice.

• Snow melts and evaporates between the rocks in the crevice.

• Air pollution in the area causes a reaction that widens the crevice.

Answer explanation

This is called ice wedging, which is a type of mechanical or physical weathering, since the rock is broken down due to a physical process.

Tags

NGSS.MS-ESS2-2

Janelle hikes along the beach every morning at the same time. Throughout the month, she notices the shoreline follows a pattern of receding and advancing.

What causes the shoreline to follow this pattern?

• Tides

• Water cycle

• Chemical weathering

• Erosion and deposition

Answer explanation

The water cycle shows the continuous movement of water within the Earth and atmosphere

Chemical weathering is the the breaking down of rocks caused by chemical reaction (for example, rusting).

Why should experiments be replicable?

• So that the materials used can be validated.

• So that scientists can gain popularity in the community.

• So that fewer errors will be made and the data appear to be more correct.

• So that others can repeat the experiment and obtain similar results.

Answer explanation

Remember "replicable" means "repeatable."

Scientists repeat their experiments to validate their results. If you follow the same steps but get different results each time, you might be doing something wrong!

As a river enters a larger body of water, sediments are deposited over a wide area. Which of these landforms is likely to be formed at the site of deposition?

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Tags

NGSS.MS-ESS2-2

NGSS.MS-ESS2-1

Which type of force could be used to pull up on a metal paper clip without touching it?

• Force of friction

• Force of gravity

• Magnetic force

• Elastic force

Answer explanation

Bonus point!

Magnetic force is a __________ force.

Options:

Contact

or

Noncontact?

Tags

NGSS.MS-PS2-5

Which of the following describes motion caused by a contact force

• A sailboat moving on a lake.

• A marble rolling down a sloped board.

• A leaf falling to the ground from a tree.

• Iron fillings being pulled by a magnet.

Answer explanation

All the other options were noncontact forces because there was no physical contact between the objects.

Herberto wanted to compare the gravity on the Moon to the gravity on Earth. Which statement below is correct?

• The gravity on Earth is less than the gravity on the Moon.

• The gravity on Earth is greater than the gravity on the Moon.

• The gravity on Earth is equal to the gravity on the Moon

• The gravity on Earth is the same as the gravity on the Moon

Answer explanation

Earth has a greater gravitational pull than the moon simply because the Earth is more massive.

The greater an object's mass, the more gravitational force it exerts.

Bonus point: What is the other factor that affects how strong the force of gravity is between objects?

Nikki and Lisa wanted to see if different size wheels made their skateboards go faster. They always used the same course. Their results are shown in the table.

Which of the following conclusions is supported by Tara’s and Lisa’s data?

• Skateboards with big wheels move faster.

• Skateboards with small wheels move faster.

• Wheel size does not affect the speed of a skateboard.

• What the wheels are made from has more of an affect than their size.

Tags

NGSS.MS-ETS1-3