Unit 1 Test Part B

A boy rides a skateboard. Which statement best describes how his energy changes as he moves?

• Potential energy increases from point X to point Y and kinetic energy decreases from point Y to point Z.

• Potential energy decreases from point X to point Y and kinetic energy decreases from point Y to point Z.

• Kinetic energy of his motion from point X to point Y is converted to a force that moves him up the hill to point Z

• Potential energy of his motion from point X to point Y is converted to a force that moves him up the hill to point Z

Answer explanation

As the boy rides from point X to Y, he descends, causing potential energy to decrease. From Y to Z, he slows down, leading to a decrease in kinetic energy. Thus, the correct choice is that potential energy decreases from X to Y and kinetic energy decreases from Y to Z.

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NGSS.MS-PS3-5

According to Newton's Third Law of Motion, when a hammer strikes and exerts a force on a nail, the nail...

• creates a friction with the hammer

• disappears into the wood

• exerts an equal force back on the hammer

• moves at a constant speed

Answer explanation

According to Newton's Third Law of Motion, for every action, there is an equal and opposite reaction. When the hammer strikes the nail, the nail exerts an equal force back on the hammer.

Tags

NGSS.MS-PS2-1

Caitlyn, Corona, and Inyoung take turns hitting a ball with the same bat. At the moments that they hit the balls, their bats are swinging at different speeds. Whose bat hits the ball with the most force?

• Caitlyn, whose bat is speeding up at the moment it hits the ball.

• Corona, whose bat is slowing down at the moment it hits the ball.

• Inyoung, whose bat is swinging at a steady speed at the moment it hits the ball.

• All three will hit the ball with the same amount of force.

Answer explanation

Caitlyn's bat is speeding up at the moment it hits the ball, which increases the force applied to the ball. In contrast, Corona's bat is slowing down, and Inyoung's bat is at a steady speed, resulting in less force.

Tags

NGSS.MS-PS2-1

NGSS.MS-PS2-2

Priyanka held two magnets together and noticed a force between them. This force surrounding a magnet is known as the magnetic

• surface

• surrounding

• field

Answer explanation

The force surrounding a magnet is called the magnetic field. This field is responsible for the attraction or repulsion between magnets, which Priyanka observed when she held them together.

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The closer you are to the magnet the

• weaker

• stronger

Answer explanation

The closer you are to a magnet, the stronger its magnetic field affects you. Therefore, the correct answer is 'stronger'.

Tags

NGSS.MS-PS2-3

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Claire threw the ball and it hit her mother's vase. Energy transferred from the moving ball to the stationary vase, causing the vase to knock over. This is an example of Energy Transfer. Which laws can also be used to describe these actions? Check all that apply.

• Universal Law of Gravitation

• Newton's Laws of Motion

• The Law of Conservation of Energy

• Hubble's Law of Cosmic Expansion

Answer explanation

Newton's Laws of Motion describe the relationship between the ball's motion and the vase's reaction. The Law of Conservation of Energy explains how energy is transferred from the ball to the vase, causing it to fall.

Tags

NGSS.MS-PS2-1

NGSS.MS-PS3-1

NGSS.MS-PS3-5

Neil is an astronaut. At the doctor's office, his weight was 180 pounds. When Neil landed on the moon, his steps were lighter and his weight was only 30 pounds. Consider this evidence and develop a claim as to why the change occurred.

Answer explanation

Neil's weight decreased from 180 pounds to 30 pounds due to the moon's lower gravity, which is about 1/6th that of Earth's. This reduction in gravitational force makes objects weigh less, explaining his lighter steps on the moon.

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NGSS.MS-ESS1-2

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Maggie found two magnets on the ground. She examined the magnets and noticed that the poles are not labeled on the magnets. She decided to hold the two ends of the magnet together to observe the forces. Based on this evidence, develop a claim about which ends of the magnets were interacting.

Answer explanation

Since magnets have opposite poles that attract, if Maggie held the two ends together and they interacted positively, it indicates that one end was a north pole and the other was a south pole.

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What happens to the magnetic force when the distance between two magnets is increased?

• The force becomes stronger

• The force becomes weaker

• The force remains the same

Answer explanation

The magnetic force between two magnets decreases as the distance between them increases. This is due to the inverse square law, which states that force diminishes with the square of the distance, making the force weaker.

Tags

NGSS.MS-PS2-3

Which of the following best describes the energy transformation when a ball is thrown upwards?

• Potential energy is converted to thermal energy

• Thermal energy is converted to kinetic energy

• Potential energy is converted to kinetic energy

• Kinetic energy is converted to potential energy

Answer explanation

When a ball is thrown upwards, its kinetic energy (due to motion) is converted into potential energy (due to height). As it rises, the speed decreases, and thus kinetic energy decreases while potential energy increases.

Tags

NGSS.MS-PS3-5