Transcript File
Newton’s First and Second Laws of Motion Chapter 12 Section 2 Newton’s First Law Also known as The Law of Inertia O The state of motion of an object does not change as long as the net force acting on the object is zero. Newton’s 1st law O An object in motion tends to stay in motion O In a straight line at a constant speed O And an object at rest tends to stay at rest O Unless acted upon by an outside force O It requires a push or pull in order to change an objects state of motion!!! Newton’s 1st law O Inertia is the tendency of an object to resist a change in motion. O ESA Video Newton’s 2nd Law O The acceleration of an object is equal to the force you apply divided by the mass of the object. Newton's Second Law O If you apply more force to an object, it accelerates at a higher rate. O Force is directly proportional to acceleration. Newton's Second Law O If an object has more mass it accelerates at a lower rate because mass has inertia. O The more mass the less acceleration; mass is indirectly proportional to acceleration. Newton’s 2nd Law O ESA video #2 Newton's Second Law Newton’s 2nd Law • How much force is needed to accelerate a 1400 • • • • • kilogram car 2 meters per second/per second? Write the formula F=mxa Fill in given numbers and units F = 1400 kg x 2 meters per second/second Solve for the unknown • 2800 kg-meters/second/second or N 2800 Practice Problems • 1. What acceleration will result when a 12 N net force applied to a 3 kg object? A 6 kg object? • 2. A net force of 16 N causes a mass to accelerate at a rate of 5 m/s2. Determine the mass. • 3. How much force is needed to accelerate a 66 kg skier 1 m/sec/sec? • 4. What is the force on a 1000 kg elevator that is falling freely at 9.8 m/sec/sec? Practice Problems-ANSWERS • 1. What acceleration will result when a 12 N net force applied to a 3 kg object? A 6 kg object? • 4m/s 2; 2m/s 2 • 2. A net force of 16 N causes a mass to accelerate at a rate of 5 m/s2. Determine the mass. • 3.2 kg • 3. How much force is needed to accelerate a 66 kg skier 1 m/sec/sec? • 66N • 4. What is the force on a 1000 kg elevator that is falling freely at 9.8 m/sec/sec? • 9800N Now Try on your own!!! Review: O If mass stays the same, and you INCREASE the force applied to an object, what happens to the acceleration of the object? O If the force applied to an object stays the same, but the mass is increased, what happens to the acceleration? Mass Vs. Weight O Mass is the amount of matter present in an object. Measured in Kg. O Weight is the effect of gravity on an object’s mass. Measured in Newtons O Gravity on Earth is 9.8 m/s2 or 9.8 N/Kg) O Mass does NOT change. O Weight DOES change as gravity changes O Weight equals mass times the acceleration due to gravity. O W=mxg O Remember, gravity is different on other planets!