7th grade study guide for post test

Which of the following is the best description of an energy transformation that occurs in a light bulb?

• Light energy is transformed into mechanical energy.

• Electrical energy is transformed into light and heat energy.

• Heat energy is transformed into light energy.

• Chemical energy is transformed into electrical energy.

Answer explanation

The correct choice is that electrical energy is transformed into light and heat energy in a light bulb. This process occurs when electricity flows through the filament, producing both light and heat.

Which statement best describes what happens to a snow skier's potential energy while gliding down a ski slope?

• Potential energy is created in an amount equal to the change in elevation as the skier moves down the slope.

• Potential energy is destroyed at a rate equal to the speed the skier travels down the slope.

• Potential energy is conserved and has an equal value at the top and bottom of the slope.

• Potential energy is transformed into an equal amount of kinetic energy as the skier moves down the slope.

Answer explanation

As the skier descends, potential energy decreases due to a drop in elevation, while kinetic energy increases. This transformation occurs in a way that the total mechanical energy remains constant, illustrating energy conservation.

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NGSS.MS-PS3-2

NGSS.MS-PS3-5

Why should a scientist repeat the same experiment several times before reporting the results?

• to prevent other scientists from duplicating his work

• to ensure the results are valid and did not happen by accident

• to formulate a reliable hypothesis

• to verify that the notes taken during the experiment are accurate

Answer explanation

Repeating experiments helps ensure that results are consistent and not due to random chance. This validation is crucial for scientific credibility, making the correct choice 'to ensure the results are valid and did not happen by accident'.

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NGSS.MS-LS2-4

If a theory is widely accepted by the scientific community and new empirical data and evidence are discovered that does not fit in with the current theory, what usually happens?

• The theory is discarded.

• The theory is changed to fit the new data.

• The scientist must have made a mistake.

• The new evidence is rejected.

Answer explanation

When new empirical data contradicts a widely accepted theory, the scientific community typically revises the theory to accommodate the new evidence, rather than discarding it outright or rejecting the evidence.

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NGSS.HS-PS1-2

On some small islands in the Pacific Ocean, the average sea level is rising on the beaches little by little each year. Residents of the islands are worried that their island, and their homes, may become flooded in a few years. What is the most likely cause for the water level increases?

• The waves are bigger because of increased winds.

• Ice from the North and South poles is melting and adding to the water in the ocean.

• They are getting more rain in their area.

• The tides are more dramatic because of the number of full moons they have experienced.

Answer explanation

The most likely cause of rising sea levels is the melting of ice from the North and South poles, which adds more water to the ocean. This is a significant factor in global sea level rise, affecting low-lying islands.

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NGSS.HS-ESS3-1

NGSS.HS-ESS3-5

When a warm air mass and cold air mass come together, like a warm front and cold front, a typical outcome is rain. What explains why rain forms in this situation?

• The cold air causes the moisture in the warm air to condense and precipitate as rain.

• The two air masses neutralize each other, which results in clouds that produce rain.

• The cold air is moving faster than the warm air, which causes rain.

• Because the cold air is denser, it causes rain.

Answer explanation

When warm and cold air masses meet, the cold air forces the warm air to rise. As the warm air rises, it cools, causing the moisture in it to condense into droplets, leading to rain. Thus, the correct choice explains this process.

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NGSS.MS-ESS2-5

Convection currents in the atmosphere influence many weather patterns. What property of the air has the most influence on convection currents?

• the direction of the wind

• the velocity of the wind

• the temperature of the air

• the mass of the air

Answer explanation

The temperature of the air is the most influential property on convection currents. Warmer air rises, creating movement, while cooler air sinks, driving the circulation that affects weather patterns.

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NGSS.MS-ESS2-6

NGSS.MS-ESS2-5

Joshua thinks that global climate change is not happening because a city in Northern Florida received snow one day in January. Which statement explains what is wrong with Jason's reasoning?

• Northern Florida would need to get snow for at least a week for this to be true.

• Jason has confused the weather for one day with the climate of a region.

• The climate of Northern Florida would be unaffected since it's already warm in Florida.

• Jason does not realize that Southern Florida would also need to receive snow to make this true.

Answer explanation

Jason's reasoning is flawed because he is confusing a single day's weather event (snow in Northern Florida) with the long-term climate of the region, which is generally warm. Climate is determined by long-term patterns, not isolated incidents.

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NGSS.MS-ESS2-6

The atmosphere surrounding Earth helps to maintain the various climates found around the world and keeps Earth from becoming extremely cold all over. How does the atmosphere help to keep Earth insulated and warm?

• The atmosphere helps spread the warmth from the water near the equator to other parts of Earth.

• The atmosphere helps trap heat energy from the Sun and energy radiated from Earth to maintain the climate.

• The atmosphere creates heat as Earth moves through space, helping to insulate Earth.

• The atmosphere traps the heat generated by Earth's core and helps maintain Earth's climate.

Answer explanation

The atmosphere traps heat energy from the Sun and the energy radiated from Earth, which helps maintain the planet's climate and keeps it warm, preventing extreme cold.

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NGSS.MS-ESS2-6

Wind is caused by which of the following?

• the uneven heating of Earth's surface

• the gravity of the Sun

• the Moon's attraction to Earth

• the changes in the ozone layer

Answer explanation

Wind is primarily caused by the uneven heating of Earth's surface, which creates differences in air pressure. This pressure difference leads to air movement, resulting in wind.

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NGSS.MS-ESS2-6

NGSS.MS-ESS2-5