Newton’s Laws

Sir Isaac Newton Studied physics in the late 1600’s Studied physics in the late 1600’s Developed laws about force and gravity Developed laws about force and gravity Discovered that a prism could separate light into the color spectrum and vice-versa and proved that color is a property of light Discovered that a prism could separate light into the color spectrum and vice-versa and proved that color is a property of light Founded calculus Founded calculus

Newton’s First Law An object at rest stays at rest and an object in motion stays in motion unless acted on by an outside unbalanced force. An object at rest stays at rest and an object in motion stays in motion unless acted on by an outside unbalanced force. Think about slamming on the brakes in the car – the car slows down, but you don’t – locks the seatbelt. Think about slamming on the brakes in the car – the car slows down, but you don’t – locks the seatbelt.

Inertia Inertia – the tendency of an object to resist a change in its motion Inertia – the tendency of an object to resist a change in its motion In order to overcome an object’s inertia, a force must be exerted on the object. In order to overcome an object’s inertia, a force must be exerted on the object. Newton’s 1 st Law is also called the Law of Inertia Newton’s 1 st Law is also called the Law of Inertia Newton's First Law of Motion Newton's First Law of Motion Newton's First Law of Motion Newton's First Law of Motion

Law of Inertia Click box to play video Click box to play video

Newton’s Second Law Force equals mass x acceleration Force equals mass x accelerationF=ma Explains how objects behave when forces are unbalanced Explains how objects behave when forces are unbalanced

Newton’s Third Law Forces come in pairs Forces come in pairs For every action, there is a reaction For every action, there is a reaction

Newton’s Third Law Think about Think about A rocket being launched A rocket being launched Click Below for video

Galileo Galileo was a scientist who studied math and physics in the late 1500’s and early 1600’s in Italy Galileo was a scientist who studied math and physics in the late 1500’s and early 1600’s in Italy He showed that objects with unequal masses would fall to the ground at the same time by doing an experiment at the Leaning Tower of Pisa He showed that objects with unequal masses would fall to the ground at the same time by doing an experiment at the Leaning Tower of Pisa

Mass and Weight Mass is the amount of matter in an object – usually measured in g or kg Mass is the amount of matter in an object – usually measured in g or kg Mass does not change with gravity Mass does not change with gravity Weight is the force of gravity on an object – measured in N Weight is the force of gravity on an object – measured in N Weight changes with gravity, so it can be different in different places Weight changes with gravity, so it can be different in different places

Calculating Weight F g =weight F g =weight F g =mg F g =mg This formula is on your reference table This formula is on your reference table The value of g is on your reference table The value of g is on your reference table

Calculating Weight An object with a mass of 12kg on Earth will have a mass of 12kg on the moon. Calculate the weight of the object on earth. An object with a mass of 12kg on Earth will have a mass of 12kg on the moon. Calculate the weight of the object on earth. F g =mg F g =mg F g =12kg · 9.8m/s 2 = 117.6N F g =12kg · 9.8m/s 2 = 117.6N

Calculating Weight An astronaut has a mass of 90kg. Find his weight if he is in a flight simulator with a gravitational pull of 1.0m/s 2. An astronaut has a mass of 90kg. Find his weight if he is in a flight simulator with a gravitational pull of 1.0m/s 2. F g =mg F g =mg F g =90kg · 1.0m/s 2 = 90N F g =90kg · 1.0m/s 2 = 90N