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Section 1 Laws of Motion. Chapter 11. Newton’s First Law. Newton’s first law of motion states that an object at rest remains at rest and an object in motion maintains its velocity unless it experiences an unbalanced force. Objects tend to maintain their state of motion.
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Section 1 Laws of Motion Chapter 11 Newton’s First Law • Newton’s first law of motionstates thatan object at rest remains at rest and an object in motion maintains its velocity unless it experiences an unbalanced force. • Objects tend to maintain their state of motion. • Inertiais the tendency of an object to resist being moved or, if the object is moving, to resist a change in speed or direction until an outside force acts on the object.
Section 1 Laws of Motion Chapter 11 Newton’s First Law
Section 1 Laws of Motion Chapter 11 Newton’s First Law, continued • Inertia is related to an object’s mass. Mass is a measure of inertia. • Seat belts and car seats provide protection. • Because of inertia, you slide toward the side of a car when the driver makes a sharp turn. • When the car you are riding in comes to a stop, your seat belt and the friction between you and the seat stop your forward motion.
Section 1 Laws of Motion Chapter 11 Mass and Inertia
Section 1 Laws of Motion Chapter 11 Newton’s Second Law • Newton’s second law of motionstates that the unbalanced force acting on an object equals the object’s mass times its acceleration. • Force equals mass times acceleration. Force = mass acceleration F = ma • Force is measured in newtons (N). 1 N = 1 kg 1 m/s2
Section 1 Laws of Motion Chapter 11 Newton’s Second Law
Section 1 Laws of Motion Chapter 11 Newton’s Second Law
Section 1 Laws of Motion Chapter 11 Math Skills Newton’s Second Law Zookeepers lift a stretcher that holds a sedated lion. The total mass of the lion and stretcher is 175 kg, and the lion’s upward acceleration is 0.657 m/s2. What is the unbalanced force necessary to produce this acceleration of the lion and the stretcher? 1. List the given and unknown values. Given: mass, m = 175 kg acceleration, a = 0.657 m/s2 Unknown: force, F = ? N
Section 1 Laws of Motion Chapter 11 Math Skills, continued 2. Write the equation for Newton’s second law. force = mass acceleration F = ma 3. Insert the known values into the equation, and solve. F = 175 kg 0.657 m/s2 F = 115 kg m/s2 = 115 N
Section 1 Laws of Motion Chapter 11 Newton’s Second Law, continued • Newton’s second law can also be stated as follows: The acceleration of an object is proportional to the net force on the object and inversely proportional to the object’s mass.