Newton's Laws Review

During a demonstration of Newton’s laws of motion, a student used the setup shown in Figure 1. The student flicked the index card with a fingertip, and the coin fell straight down into a plastic cup as shown in Figure 2. Which of these best explains why the coin fell straight down into the cup instead of remaining on the index card?

• The coin was at rest until the card was removed, so it tended to remain in the same location. Once the card was gone, the unbalanced force of gravity caused the coin to fall.
• Moving the card applied an action force on the coin. Since the card was gone, gravity applied a reaction force on the coin.
• The card had less mass than the coin, so a smaller force of gravity acted on the card. The larger force of gravity on the coin made it fall.
• The acceleration of the coin falling into the cup was equal and opposite to the acceleration of the card.

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According to Newton’s Law of Inertia, which of the following objects will change its motion?

• A bike rider on a smooth and level road, pedaling at a constant rate.
• A train pulling on another train, each with the same amount of force.
• A chair sitting on the floor with balanced forces acting in opposite directions.
• A ball rolling across the floor with friction acting in the opposite direction.

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Safety belts protect people in cars in the event of an accident because, according to Newton’s Laws of Motion, when an impact causes the car to suddenly change its motion, -

• the people in the car will continue to move in the same direction and at the same speed as before the impact.
• the speed of the car always increases, giving it greater force since the mass will remain the same.
• the speed of the people always increases, since now they have, not one, but two forces acting on them.
• the car now has a greater overall mass - its own mass plus the mass of the object by which it has been struck.

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According to Newton’s Law of Inertia, an object that is moving will change its motion only if what kinds of forces act on it?

• Constant forces
• Unbalanced forces
• Unbalanced forcesStrong forces
• Gravitational forces

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A bowling ball is rolled with a certain speed and strikes a bowling pin with a force indicated by the arrow in this illustration. When the bowling ball strikes the bowling pin, the force applied by the pin to the ball -

• depends on the mass of the bowling pin.
• is equal to the force applied by the ball.
• must be zero, since the pin is not moving.
• is equal to the force of gravity on both.

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According to Newton's Second Law, How do you calculate force?

• Multiply mass and acceleration

• Divide mass by acceleration

• Divide acceleration by mass

• Divide force by mass

The roller coaster car begins to move due to

• Newton's first law of motion

• Newton's second law of motion

• Newton's third law of motion

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The roller coaster car changes direction due to

• balanced forces

• an unbalanced force applied

• an action and reaction force

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You will want a lot of friction

• at the start of the roller coaster

• as the roller coaster turns

• at the end of the roller coster

If 2 roller coaster cars race, the car with greater mass will have a lower acceleration. This is an example of Newton's ___ Law of Motion.

• first

• second

• third

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