Exit Ticket - Exploring Newton's Laws in Motion

Which of Newton's laws states that an object at rest stays at rest unless acted upon by an unbalanced force?

• Newton's Second Law

• Newton's Third Law

• Newton's First Law

• Newton's Law of Gravitation

Answer explanation

Newton's First Law states that an object at rest remains at rest unless acted upon by an unbalanced force. This law emphasizes the concept of inertia, which is the tendency of objects to resist changes in their state of motion.

What is the formula that represents Newton's Second Law of Motion?

Answer explanation

Newton's Second Law of Motion states that the force (F) acting on an object is equal to the mass (m) of the object multiplied by its acceleration (a). Thus, the correct formula is F = ma.

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NGSS.HS-PS2-1

In a rocket launch, hot gases are expelled downward from the rocket engine. According to Newton's Third Law, what happens to the rocket?

• The rocket stays still because the forces are equal

• The rocket moves downward along with the gases

• The rocket moves upward as a reaction to the expelled gases

• The rocket slows down due to gravity

Answer explanation

According to Newton's Third Law, for every action, there is an equal and opposite reaction. When the rocket expels gases downward, it experiences an upward force, causing it to move upward as a reaction to the expelled gases.

Which of the following best describes the role of a seatbelt during a sudden car stop?

• It pushes the passenger forward to match the car's deceleration

• It applies a backward force on the passenger to counteract their forward inertia

• It increases the speed of the passenger to match the car

• It reduces the mass of the passenger to slow them down

Answer explanation

The correct choice states that the seatbelt applies a backward force on the passenger, counteracting their forward inertia during a sudden stop. This prevents injury by keeping the passenger securely in place.

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NGSS.HS-PS2-1

Answer explanation

Using Newton's second law, F = ma, we can find acceleration (a) by rearranging the formula to a = F/m. Here, F = 20 N and m = 0.5 kg. Thus, a = 20 N / 0.5 kg = 40 m/s². The correct answer is 40 m/s².

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NGSS.HS-PS2-1

On a roller coaster loop, riders feel pressed into their seats at the bottom of the loop. Which of Newton's laws best explains why riders feel heavier at the bottom of the loop?

• Newton's First Law, because the riders are at rest

• Newton's Third Law, because the seat pushes back on the rider

• Newton's Second Law, because the net force causes centripetal acceleration toward the center of the loop

• Newton's First Law, because the riders resist the change in direction

Answer explanation

Newton's Second Law explains that the net force acting on the riders at the bottom of the loop causes centripetal acceleration. This force makes them feel heavier as the seat pushes up against them, increasing their apparent weight.

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During a swimming race, a swimmer pushes backward against the water with their hands. How does Newton's Third Law explain the swimmer's forward movement?

• The water absorbs the force, allowing the swimmer to glide forward

• The water pushes forward on the swimmer with an equal and opposite force

• The swimmer's inertia carries them forward without any reaction force

• The swimmer's mass decreases, making it easier to move forward

Answer explanation

According to Newton's Third Law, when the swimmer pushes backward against the water, the water exerts an equal and opposite force forward on the swimmer, propelling them ahead.

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NGSS.MS-PS2-1

Two tectonic plates collide with equal and opposite forces. One plate is denser and subducts beneath the other. Which combination of Newton's laws best explains this interaction?

• Only Newton's First Law explains the collision

• Newton's Second and Third Laws explain the collision and subduction

• Only Newton's Third Law explains the subduction

• Newton's First and Second Laws explain why the plates were moving and then stopped

Answer explanation

Newton's Second Law explains the forces acting on the plates, while Newton's Third Law describes the equal and opposite reactions during the collision and subduction process, making this combination the best explanation.

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NGSS.HS-PS2-1

• Increasing the time of deceleration increases the force on the passenger, spreading it over a larger area

• Increasing the time of deceleration decreases the rate of change of velocity, thereby reducing the force experienced by the passenger

• The airbag increases the mass of the passenger, reducing the acceleration

• The airbag removes all forces acting on the passenger during the collision

Answer explanation

Increasing the time of deceleration allows the passenger to slow down more gradually, which decreases the rate of change of velocity. According to Newton's Second Law, this results in a lower force experienced by the passenger, reducing injury.

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NGSS.HS-PS2-3

Answer explanation

The net force on the gymnast is 600 N (upward) - 500 N (downward due to gravity) = 100 N. Using F = ma, a = F/m = 100 N / 50 kg = 2 m/s². Thus, her upward acceleration is 2 m/s².

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NGSS.HS-PS2-1