Forces & Electricity Review - CBA 2

This is an illustration of a circuit. How can the light bulb be turned on?

• connect another wire from the battery to the switch

• disconnect one of the wires from the battery

• move the light bulb to another part of the circuit

• push down the switch to close the circuit

Answer explanation

To turn on the light bulb, you need to push down the switch to close the circuit. This action allows electricity to flow from the battery through the circuit, lighting the bulb.

Observe the diagram. When the switch is closed, the bulb does not light up. How could the circuit be changed so that the bulb will light?

• Remove the switch from the circuit.

• Remove the wire in the diagram that connects the battery and the light bulb.

• Move one of the wires from the positive (+) terminal of the battery to the other end of the switch.

• Move both wires from the positive (+) terminal of the battery to the other end of the switch.

Answer explanation

Moving one wire from the positive terminal of the battery to the other end of the switch creates a complete circuit, allowing current to flow and the bulb to light up. The other options do not establish a proper connection.

Kyle is investigating the properties of three drinking cups labeled A, B, and C. In an experiment, he fills each cup with water that has been kept cold in the refrigerator. Then he places the cups of water on a tray in his kitchen. He measures the temperatures of the water every five minutes for 25 minutes. The table shows his results. Which statement best explains Kyle’s results?

• Cup A is the largest cup, Cup B is smaller, and Cup C is the smallest.

• Cup A was kept sealed, while the other cups were open to the air.

• Cup C is made of a thermal insulator, such as thick foam or thick plastic.

• Cup C is made of a thermal conductor, such as a metal.

Answer explanation

Cup C is made of a thermal conductor, which allows heat to transfer quickly, causing the water temperature to rise faster than in the other cups. This explains why Cup C's temperature increased more than Cups A and B.

Duck 1 and Duck 2 are each floating in a lake. Then the wind speed increases on the lake for Duck 2, causing the waves to be taller and move faster. Which duck will the waves carry a farther distance?

• Duck 1 will travel farther because its waves are shorter.

• Duck 2 will travel farther because its waves are taller.

• Duck 2 will travel farther because its waves are faster.

• Neither duck will travel forward with the waves.

Answer explanation

Duck 2 will travel farther because its waves are faster. Faster waves can carry the duck more effectively across the lake, leading to greater distance traveled compared to Duck 1, which has shorter waves.

Which event is an example of the energy of motion being transferred from one object to another object?

• A paper airplane crumples when it strikes a tree trunk.

• A hammer is used to pound a nail into a board.

• A boy plays a video game on a cell phone.

• A dinner plate breaks into pieces when it falls on a hard floor.

Answer explanation

A hammer transferring its energy to the nail demonstrates the energy of motion being transferred. The hammer's motion drives the nail into the board, clearly illustrating this concept.

Observe the illustration. Alan is investigating the forces between bar magnets. He places the magnets side by side in each of the two arrangements shown here. What can he learn by observing the changes to the magnets?

• The force between two magnets depends on how their poles face each other.

• The force between two magnets is always the same, regardless of how their poles face each other.

• The N poles of magnets always attract, while the S poles always repel.

• The N poles of magnets always repel, while the S poles always attract.

Answer explanation

By observing the magnets, Alan can learn that the force between them varies based on how their poles are aligned. Opposite poles attract, while like poles repel, demonstrating that pole orientation is crucial in magnetism.

Observe the photo. Brianne is using an hourglass to investigate the force of gravity on sand. For the hourglass shown here, she observes that the sand inside it falls to the bottom of the hourglass in 2 minutes. How could Brianne make the sand take longer than 2 minutes to fall?

• She could time the hourglass somewhere above the ground, such as the top of a skyscraper.

• She could stop observing the hourglass while the sand falls.

• She could hold the hourglass at an angle.

• She could time the hourglass somewhere below the ground, such as a basement.

Answer explanation

Holding the hourglass at an angle would slow the flow of sand, making it take longer than 2 minutes to fall. The other options do not affect the time it takes for the sand to fall.

A soccer ball is kicked. The ball rolls across the grass. How does friction act on the ball?

• Friction pulls the ball down a hill, even if the ball is rolling up a hill.

• Friction resists the ball’s motion when the ball is kicked and then does not act on the ball.

• Friction is constantly pushing the ball forward in the same direction as it rolls.

• Friction is constantly pushing against the rolling ball and slows it down.

Answer explanation

Friction acts against the motion of the ball, slowing it down as it rolls across the grass. This is why the correct choice is that friction is constantly pushing against the rolling ball and slows it down.

Michaela tests the falling times of different objects. She drops each object from the same height. The table shows her results. What conclusion do Michaela's results support?

• Mass affects the falling time of an object.

• Shape affects the falling time of an object.

• The force of gravity only affects some objects.

• The force of gravity only pulls on objects when they are falling.

Answer explanation

Michaela's results indicate that the shape of the objects influences their falling times, as different shapes can create varying air resistance, affecting how quickly they fall. Thus, the correct conclusion is that shape affects the falling time of an object.

Nadine has a mixture of two materials. She plans to use a magnet to separate the mixture. What criteria are needed for her plan to succeed? Select TWO correct answers.

• One of the materials must be magnetic.

• One of the materials must be nonmagnetic.

• One of the materials must be liquid.

• Both materials must be in pieces of the same size.

• Both materials must be in pieces of different sizes.

Answer explanation

For Nadine's plan to succeed, one material must be magnetic to be attracted to the magnet, while the other must be nonmagnetic to remain unaffected. This allows for effective separation of the two materials.