NEWTON’S 3rd LAW

Newton’s 3rd Law and Gravity -Newton’s 1st law stated: An object at rest tends to ____________________________ an object in motion tends to __________________________ as long as the forces are balanced. stay at rest stay in motion -Newton’s 2nd law states (part 1): When an unbalanced force acts on an object, the object will ___________________ in the direction that the unbalanced force points. -Newton’s 2nd law states (part 2): Force = __________ x ___________________ accelerate acceleration mass

equal force (This is called recoil or kickback) -Newton’s 3rd law states: -whenever an object exerts a force on a second object, the second object exerts an ___________________ back on the first object. equal force -Commonly stated as: For every action there is an equal and opposite reaction. (This is called recoil or kickback)

Push hot gases The 3rd Law says out the back of the gases must push -Rocket Motion -On Earth we use air and Bernoulli’s principle to allow flight. Since there is no air in space, how can a vehicle be propelled? Push hot gases out the back of the rocket The 3rd Law says the gases must push equally back on you and your rocket.

object falling forever. -Gravity -Gravitational force (or gravity) is the force of ____________ that exists between any two pieces of _____________. -Gravity on Earth is always in affect, pulling all objects towards the center of the Earth. attraction matter . -An orbit is just an object falling forever.

masses distance big small very big very small -The attraction of objects with the Earth is just one example of gravity at work. According to Newton, any two objects that are composed of matter attract each other, but there are rules for the strength of this attraction. -Universal Law of Gravitation states: -the amount of gravitational force between two objects depends on two things: 1) the ___________ of the objects and 2) the ___________ between the objects masses distance -Big masses = _______ g. force -Big distance = ________ g. force -Big masses & short distance = _____________ g. force -Small masses & large distance = _____________ g. force big small very big very small

Weight = ____________ x _____________________ -Weight and mass are NOT the same. -Mass is constant and measures the amount of _____________. -Weight is just a measure of the _______________ on an object. -since the larger mass = larger attraction, the more mass an object has the more weight it has. matter gravitational force Weight = ____________ x _____________________ W = ___ x ___ - On Earth, gravity accelerates all objects at _________. Ex. How much does an 80 kg man weigh on earth? gravitational acceleration mass (N) (kg) (N/kg) m g ~10 m/s2 m = 80kg g = 10 m/s2 W = m x g W = 80kg x 10 m/s2 W = 800 kg x m/s2 = 800 N -However, since weight depends on the gravitational force between the two objects (ex. yourself and Earth) your weight will change if you leave Earth. -Weight on the moon is about ______ of the weight on Earth. 1/6