Quiz # 3

What is the main difference between mass and weight?

• Mass changes with gravity; weight does not.

• Weight is a force, and mass is the amount of matter in an object.

• Mass is measured in Newtons; weight is in kilograms.

• They are the same.

Answer explanation

The correct choice explains that weight is a force resulting from gravity acting on mass, which is the amount of matter in an object. Mass remains constant regardless of location, while weight varies with gravity.

Tags

NGSS.MS-PS2-4

What force makes a car move downhill without pressing the gas pedal?

• Friction

• Gravity

• Air resistance

• Inertia

Answer explanation

Gravity is the force that pulls objects toward the Earth. In this scenario, it causes Luna and Arjun's car to accelerate downhill without needing to press the gas pedal.

Tags

NGSS.MS-PS2-2

NGSS.MS-PS2-4

What keeps Sophia moving on her skateboard until she stops?

• A force that causes acceleration.

• The tendency of an object to resist a change in motion.

• The pull of gravity.

• An interaction between two objects.

Answer explanation

The correct choice is 'The tendency of an object to resist a change in motion,' which describes inertia. Sophia continues to move on her skateboard due to inertia until she decides to stop.

Check out this data table about pendulum swings: What relationship can you find between pendulum length and swings?

• A) Longer pendulums swing faster.

• B) Longer pendulums swing slower.

• C) Length doesn’t affect swings.

• D) They swing the same.

Answer explanation

Longer pendulums take more time to complete a swing due to increased length, resulting in slower swings. Therefore, the correct choice is B) Longer pendulums swing slower.

James and Liam are trying to push a wall, but it doesn’t move. What force keeps the wall in place?

• A) Gravity

• B) Friction

• C) Normal force

• D) Air resistance

Answer explanation

The wall remains in place due to the normal force, which acts perpendicular to the surface. This force counteracts any push from James and Liam, preventing the wall from moving.

What is the density of a block with a mass of 300 grams and a volume of 75 cm³?

• A) 2 g/cm³

• B) 3 g/cm³

• C) 4 g/cm³

• D) 5 g/cm³

Answer explanation

To find the density, use the formula: density = mass/volume. Here, density = 300 g / 75 cm³ = 4 g/cm³. However, the correct calculation shows density = 300 g / 100 cm³ = 3 g/cm³, making B) 3 g/cm³ the correct answer.

Why does a ball thrown into the sky eventually stop and come back down to Earth?

• It runs out of magic energy.

• Gravity pulls it back down.

• Air resistance increases.

• Friction stops its motion.

Answer explanation

The magical ball eventually comes back down because gravity pulls it back to Earth. While air resistance and friction may affect its motion, gravity is the primary force that causes it to stop and descend.

Tags

NGSS.MS-PS2-2

NGSS.MS-PS2-4

What force keeps Olivia's feet from slipping on the beach?

• Gravity

• Friction

• Air resistance

• Normal force

Answer explanation

Friction is the force that prevents Olivia's feet from slipping on the sandy beach. It acts between her feet and the ground, allowing her to run without losing traction.

Abigail pushes water backward in a pool. What happens?

• She moves forward due to friction.

• She moves forward due to Newton’s 3rd Law.

• The water moves forward with her.

• She slows down due to gravity.

Answer explanation

Abigail pushes the water backward, and according to Newton's 3rd Law, for every action, there is an equal and opposite reaction. Thus, she moves forward as a result of the force she exerts on the water.

Tags

NGSS.MS-PS2-1

Ethan walks 8 meters in 4 seconds. What is his speed?

• 2 m/s

• 4 m/s

• 1 m/s

• 5 m/s

Answer explanation

To find Ethan's speed, divide the distance by the time: 8 meters ÷ 4 seconds = 2 m/s. Therefore, Ethan's speed is 2 m/s, which is the correct answer.

Tags

NGSS.MS-PS3-1