Newtons First Law Worksheet for 9th - 12th Grade | Lesson Planet - Free Printable

Problem Analysis:

The task involves analyzing statements related to Newton's First Law of Motion and determining whether each statement is True or False. Newton's First Law, also known as the Law of Inertia, states:

> An object at rest stays at rest, and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced (net) external force.

We will evaluate each statement based on this principle.

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Statement 1: "When a car stops suddenly, passengers are thrown forward."

- Explanation: When a car stops suddenly, the passengers tend to continue moving forward because their bodies resist changes in motion due to inertia. This is a direct consequence of Newton's First Law.
- Answer: True

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Statement 2: "A ball rolling on a flat surface slows down because it has no force acting on it."

- Explanation: A ball rolling on a flat surface slows down due to frictional forces acting between the ball and the surface. Even though the surface appears flat, there are always frictional forces present that oppose the motion. If there were truly no forces acting on the ball, it would continue rolling indefinitely (as per Newton's First Law).
- Answer: False

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Statement 3: "According to Newton’s Second Law, if there are no net forces acting on an object, then its acceleration is zero."

- Explanation: Newton's Second Law states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass (\( F = ma \)). If there are no net forces (\( F = 0 \)), then the acceleration (\( a \)) must be zero. However, this statement refers to Newton's First Law, which specifically addresses the case of zero net force leading to constant velocity (or rest). While the statement is factually correct, it incorrectly attributes the principle to Newton's Second Law.
- Answer: False

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Statement 4: "For every action force, there is an equal and opposite reaction force."

- Explanation: This statement describes Newton's Third Law of Motion, not the First Law. Newton's Third Law states that for every action, there is an equal and opposite reaction. While this is true, it is not relevant to Newton's First Law.
- Answer: False

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Statement 5: "Passengers in a car feel pushed back into their seats when the car accelerates."

- Explanation: When a car accelerates, passengers feel pushed back into their seats because their bodies resist the change in motion due to inertia. This sensation is caused by the normal force exerted by the seat on the passengers, which increases to counteract their tendency to remain stationary (inertia). This is consistent with Newton's First Law.
- Answer: True

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Statement 6: "If you apply a force greater than the force of friction, you can start an object moving."

- Explanation: To start an object moving, the applied force must overcome the static friction acting on the object. Once the applied force exceeds the maximum static friction, the object will begin to move. This is consistent with Newton's First Law, as the object will remain at rest until an unbalanced force acts on it.
- Answer: True

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Statement 7: "Rolling friction allows objects to roll faster against surfaces than sliding friction allows objects to slide."

- Explanation: Rolling friction is generally much smaller than sliding friction. This means that objects can roll more easily and often faster than they can slide across a surface. While this is a true statement about friction, it does not directly relate to Newton's First Law.
- Answer: False

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Statement 8: "Our determination of the net force acting on an object depends on our choice of coordinate system."

- Explanation: The net force acting on an object is an absolute physical quantity and does not depend on the choice of coordinate system. While the components of the force may change depending on the coordinate system, the net force itself remains invariant.
- Answer: False

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Final Answer:

\[
\boxed{\text{T, F, F, F, T, T, F, F}}
\]