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# Newton’s Laws of Motion

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Newton’s Laws of Motion

Newton’s 1st Law Definition: An object at rest remains
at rest and an object in motion maintains its position unless it experiences an Outside force.

Newton’s 1st Law Inertia is the tendency of an object at rest to remain at rest or, if moving, to continue moving with a constant velocity. All objects have inertia because they resist changes in motion. The greater the mass of the object the more force required to change it’s motion.

Concept Check 1 Why should infants be placed in special-backward facing car seats?

Newton 2nd Law Definition: The unbalanced force acting on an object equals the object’s mass times its acceleration. Mathematically represented by the equation: Force= mass x acceleration or F=ma Cenzo was here Remember the SI unit for force is a Newton Newton= 1 kg x m/s2 towards center of the earth

Free Fall Definition: the motion of a body when only the force of gravity is acting on it Acceleration near the Earth’s surface is constant. All objects on Earth accelerate at exactly 9.8 m/sec/sec. Gravity is abbreviated as g

Concept Check 2 In the absence of air resistance which will hit the ground first?

Weight Definition: The force on an object due to gravity is called its weight 1 Newton= 1 kg x m/s2 towards center of the earth= lbs or pounds

Apparent Weightlessness
Astronauts and their surroundings all accelerate at the same rate. Consequently, the floor of the shuttle pushes up against the astronauts or objects in the shuttle.

Terminal Velocity Definition: the terminal velocity reached by a falling object whose acceleration is zero. The terminal velocity of a falling body occurs during free fall when a falling body experiences zero acceleration. This is because of the retarding force known as air resistance. Air resistance exists because air molecules collide into a falling body creating an upward force opposite gravity. This upward force will eventually balance the falling body's weight. It will continue to fall at constant velocity known as the terminal velocity.

Newton’s Second Law Math Problems
1. What is the net force necessary for a 3.6 x 103 kg truck to accelerate forward at 2.0 m/s2. 2. A baseball accelerates downward at 9.8 m/s2. If the gravitational force acting on the baseball is 1.8 N, what is the baseball’s mass? 3. A bobsled and crew have a combined mass of 525 kg. If the bobsled experiences an unbalanced force of 1095 N pushing it forward, what is the bobsled’s acceleration?

Newton’s 3rd Law For every action force, there is an equal and opposite reaction force. Applies force always acts in pairs _. Principle used in rocketry.

End Check- complete on a separate sheet
1. Why won’t the elephant move? 2. What is the difference between weight and mass? 3. If the elephant has a mass of 2000 Kg and the person is pushing at 60 N what is the acceleration of the elephant?

End Check- complete on a separate sheet
4. State each of Newton’s three laws of motion in your own words and give an example that demonstrate each law 5. Explain the difference between mass and weight. Does the weight of an object ever change? If so, when? 6. Using Newton’s laws, predict what will happen when a car traveling on a icy road a. Comes to a sharp bend b. Has to stop quickly 7. How much does a 7.0 kg puppy weigh on Earth?

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