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Stop Faking It! Force & Motion. Newtons First Law of Motion n Objects in motion tend to stay in motion until something hits them n Objects at rest tend.

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Presentation on theme: "Stop Faking It! Force & Motion. Newtons First Law of Motion n Objects in motion tend to stay in motion until something hits them n Objects at rest tend."— Presentation transcript:

1 Stop Faking It! Force & Motion

2 Newtons First Law of Motion n Objects in motion tend to stay in motion until something hits them n Objects at rest tend to stay at rest unless something hits them n Lets test it - Use a ball and try for yourself!

3 You may have noticed... Things tend to keep on doing whatever theyre doing until something else hits them.

4 Forces n When you were pushing, pulling, nudging, or blowing on the ball you were causing the hits that moved the object. n These things, along with other things that change motion, are called forces.

5 Why do they do that? n INERTIA n An objects tendency to keep doing what its doing is its inertia. n An object with lots of inertia requires more force to change its motion. n An object with less inertia requires less force to change its motion.

6 Now why did the things stop??? n A FORCE called FRICTION n Your test objects stop because they hit other objects (which could even be air particles). These hits cause friction and this causes the object to come to rest.

7 Newtons Second Law of Motion n Mass n Mass - measure of an objects inertia: big inertia=big mass, small inertia=small mass n n A force acting on an object = mass of the object x acceleration of the object n n F=ma n n Larger force on small mass=large acceleration

8 Speed is related to this law: n Obtain a meter stick, a ball, and a timing device. n Start rolling the ball and begin timing when the ball reaches one end of the meter stick and stop timing when it reaches the other end. n Record the distance (I meter) and the time. n To calculate the speed of the marble, divide the distance traveled by the time it took to cover that distance. That is the objects speed!

9 Use an equation to find the speed... n Speed can be written using s for speed or r for rate, or v for velocity. n Distance traveled can be d; time can be represented by t n s= d/t, r=d/t, v=d/t, n Just know what the letters mean!

10 More info related to speed n Velocity- n Velocity-tells how fast something is going and its direction (for example 65 mph North) n Vectors- n Vectors-arrows that can show velocity, magnitude (size), and direction. n Average speed n Average speed is the what you get from s=d/t. n Instantaneous speed n Instantaneous speed is your speed at a given instance in time. n Acceleration is a change in velocity (i.e.. Change in direction or speed or both) For example, a car speeding up(which is why they call it an accelerator on the car) Another equation for you: acceleration=change in velocity/time for the change Your body can detect changes in acceleration.

11 What is Gravity? The earths pull (or force) on things (it is also a force that exists between all objects) Lets test it. Drop two things. What happened? They should have hit the ground at about the same time They should have hit the ground at about the same time When gravity is the only force applied, all objects have the same acceleration When gravity is the only force applied, all objects have the same acceleration

12 Mass vs. Weight n Mass: A measure of an objects inertia-- how hard it is to change the motion of an object If you change gravity, the mass would stay the same. If you change gravity, the mass would stay the same. n Weight: The force that gravity exerts on an object If you change gravity, the weight would also change.

13 Can distant objects influence our daily lives? Because of gravity, you have a stronger attraction to things closer to you. Youll be more attracted to something located on Earth than something located on Jupiter.

14 Are astronauts really weightless when they orbit the Earth? No, because weight is the force of Earths gravity and under normal conditions you are not ever totally away from that force.

15 How do other examples of Gravity affect things on Earth? Everything exerts some type of gravitational force on everything else. One example: The gravitational forces between the moon and the waters found on Earth are responsible for the things we call Tides! -


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