What do you know about Newton You know
What do you know about Newton? You know – the smart guy who let an apple fall on his head.
The n st 1 Law of Motion Objects at rest stay at _____, while objects in motion stay in _______ unless acted on by an outside _____. 9/30/2020 Template copyright 2005 www. brainybetty. com 2
Let’s Explore Newton’s 1 st Law • Any object not moving is said to be at rest. • I. E. – a golf ball on a tee, a chair • Moving objects keep moving unless another force acts on them. 9/30/2020 Template copyright 2005 www. brainybetty. com 3
More Thoughts on Law #1 • _______ is most often the outside or unbalanced force acting on an object • Newton’s 1 st law is also called the law of ____ • Inertia is the tendency of an object to _______ change 9/30/2020 Template copyright 2005 www. brainybetty. com 4
Mass & Inertia • ______ is a measure of inertia • The more _____ – the more inertia • A softball has less inertia than a bowling ball 9/30/2020 Template copyright 2005 www. brainybetty. com 5
Question Time • According to Newton’s 1 st law objects will stay at rest or in motion unless something acts on them. A. yes b. no • The unbalanced force most likely to act on an object is a. a push b. a pull c. friction d. gravity • The resistance to change is known as a. restivity b. gravity c. inertia • Inertia is best measured by a. volume b. gravity c. mass d. acceleration 9/30/2020 Template copyright 2005 www. brainybetty. com 6
Newton’s 2 nd Law • The ______ of an object depends on the mass of the object and the amount of force applied • A = F/M • The greater the mass the slower the _____ • _____ goes up as mass goes down 9/30/2020 Template copyright 2005 www. brainybetty. com 7
Acceleration depends on Force • The greater the ______ on an object, the greater its acceleration • The acceleration of an object is always in the same direction as the _____ 9/30/2020 Template copyright 2005 www. brainybetty. com 8
ANSWER me THIS • What force is necessary to accelerate a 70 kg object at a rate of 4. 2 m/s? • What is the acceleration of a 7 kg mass if a force of 68. 6 N is used to move it toward earth? 9/30/2020 • Using Newton’s first law of motion to explain why airbags in cars are important. Template copyright 2005 www. brainybetty. com 9
Question Time • The acceleration of an object depends on a. mass b. force c. gravity d. a and b e. a and c f. all of the above. • Acceleration depends on a. gravity b. mass c. velocity d. force. 9/30/2020 Template copyright 2005 www. brainybetty. com 10
Newton’s 3 rd Law of Motion • For every _____, there is an equal and opposite _______. • All forces act in _______. • I. E. – You sit on a chair and the chair pushes back • A swimmer pushes water back and the water propels the swimmer forward • Artillery recoil • Squid propulsion • Spacewalking 9/30/2020 Template copyright 2005 www. brainybetty. com 11
Reactions are often difficult to See • Think about a ball falling toward the earth • The pull of gravity on the ball is easy to see • But the earth is also being pushed up as well • The reason you can’t see it is the _____ of the objects 9/30/2020 Template copyright 2005 www. brainybetty. com 12
Question Time • According to Newton’s 3 rd law, all forces act by themselves. A. yes b. no • Newton’s 3 rd law is sometimes hard to see because the _____ of the objects is so different a. shape b. size c. speed 9/30/2020 Template copyright 2005 www. brainybetty. com 13
Time to Summarize • • • 9/30/2020 Newton’s 1 st law of motion states that the motion of an object will not change if no unbalanced forces act on it Objects at rest will stay at rest unless acted on by an outside force. Objects in motion stay in motion unless acted on by an outside force Inertia is the tendency of an object to resist change Newton’s 2 nd law says that the acceleration of an object depends on the mass and the force exerted on it. Newton’s 3 rd law says that for every action, there is an equal and opposite reation. Template copyright 2005 www. brainybetty. com 14
Page 162 and 165 HOMEWORK 9/30/2020 Template copyright 2005 www. brainybetty. com 15
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