Physical Science 1011 Chapter 2 Newton’s Laws of Motion

2.1 Newton’s First Law of Motion Every object continues in a state of rest, or in a state of motion in a straight line, at contanst speed, unless it is compelled to change that state by forces exerted upon it. Every object continues in a state of rest, or in a state of motion in a straight line, at contanst speed, unless it is compelled to change that state by forces exerted upon it. Usually called the Law of Inertia Usually called the Law of Inertia Essentially the same as Galileo’s idea Essentially the same as Galileo’s idea

2.2 Newton’s Second Law of Motion The acceleration produced by a net force on an object is directly proportional to the net force, is in the same direction as the net force, and is inversely proportional to the mass of the object. The acceleration produced by a net force on an object is directly proportional to the net force, is in the same direction as the net force, and is inversely proportional to the mass of the object. Acceleration = Net Force Mass

2.2 Newton’s Second Law of Motion a = F m

2.2 Newton’s Second Law of Motion

2.2 Newton’s Second Law of Motion Acceleration Due to Gravity An object in free fall accelerates toward the Earth at 10 m/s 2 (if we neglect air resistance). An object in free fall accelerates toward the Earth at 10 m/s 2 (if we neglect air resistance). We assign the letter g to acceleration due to gravity. We assign the letter g to acceleration due to gravity. g = W m W = mg

2.2 Newton’s Second Law of Motion Acceleration Due to Gravity Objects of differing masses will accelerate toward the Earth at the same rate (if air resistance is neglected). Objects of differing masses will accelerate toward the Earth at the same rate (if air resistance is neglected). This has been proven during an Apollo Mission to the Moon. A hammer and a feather were released at the same time. Both struck the ground at the same time. This has been proven during an Apollo Mission to the Moon. A hammer and a feather were released at the same time. Both struck the ground at the same time.

2.2 Newton’s Second Law of Motion Acceleration Due to Gravity A skydiver accelerates toward the ground. A skydiver accelerates toward the ground. As he does, air resistance increases to the point where it equals his weight. As he does, air resistance increases to the point where it equals his weight. The skydiver then stops accelerating and falls at a constant rate called Terminal Velocity of approximately 200 km/h (125 mi/h). The skydiver then stops accelerating and falls at a constant rate called Terminal Velocity of approximately 200 km/h (125 mi/h).

2.2 Newton’s Second Law of Motion Acceleration Due to Gravity By opening his parachute, the skydiver increases the total force of air resistance, slowing him down to a speed that allows him to land without injury. (22 km/h or 14 mi/h) By opening his parachute, the skydiver increases the total force of air resistance, slowing him down to a speed that allows him to land without injury. (22 km/h or 14 mi/h)

2.3 Forces and Interactions When you push on a wall, the wall pushes back. When you push on a wall, the wall pushes back.

2.4 Newton’s Third Law of Motion Whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first. Whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first. For every action, there is an equal and opposite reaction. For every action, there is an equal and opposite reaction.

2.4 Newton’s Third Law of Motion

2.5 Vectors and Scalars Scalars have size Scalars have size Mass, speed, volume, temperature Mass, speed, volume, temperature Vectors have size and direction Vectors have size and direction Velocity, acceleration, force Velocity, acceleration, force

2.5 Vectors and Scalars Adding Vectors

Example of Velocity Vectors

Components of Vectors