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Newtons Second Law. WarmUp 10-2-12 What effect does extra mass have on the acceleration of an object if you dont increase force Newtons First Law 1.WarmUp.

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Presentation on theme: "Newtons Second Law. WarmUp 10-2-12 What effect does extra mass have on the acceleration of an object if you dont increase force Newtons First Law 1.WarmUp."— Presentation transcript:

1 Newtons Second Law

2 WarmUp What effect does extra mass have on the acceleration of an object if you dont increase force Newtons First Law 1.WarmUp 2. SCIVID 3. Newtons 2 nd Law science notes 4.Mini Vid on 2 nd Law 5.Jumping Force Game

3 WarmUp How does the gravitation force change as you go from picture A to picture B (when the mass decreases but distance stays the same)? A. Increases B. Decreases C. Stays the same D. Doesnt change A B C WarmUp SciVid 3 rd Law Poster Bill Nye: Motion WarmUp SciVid 3 rd Law Poster Bill Nye: Motion

4 Newtons Second Law Short: Force= Mass x Acceleration Example: How much force will you need to use to push a pop machine that is 1000 kg with an acceleration of 2 meters per second per second Simple Rules: 1.The greater the f orce that is applied to an object the greater A cceleration it will have THE HARDER YOU PUSH THE MORE SOMETHING SPEEDS UP, SLOWS DOWN, OR CHANGES DIRECTION Simple Rules: 1.The greater the f orce that is applied to an object the greater A cceleration it will have THE HARDER YOU PUSH THE MORE SOMETHING SPEEDS UP, SLOWS DOWN, OR CHANGES DIRECTION F= ma A= 2000 N/ 2 kg 1000 m/s/s = If we pushed a box of kleenex ( 2kg) with the same force ( 2000N) then what would our acceleration? HINT: If not solving for force, force is always on top Newtons Second Law Math F=ma A= F/m M=F/a 2. If Force is unchanged, then the greater the M ass of an object the lower the a cceleration will be THE HEAVIER SOMETHING IS THE HARDER IT IS TO MAKE SPEED UP, SLOW DOWN, CHANGE DIRECTION 2. If Force is unchanged, then the greater the M ass of an object the lower the a cceleration will be THE HEAVIER SOMETHING IS THE HARDER IT IS TO MAKE SPEED UP, SLOW DOWN, CHANGE DIRECTION A= F/M = Draw a situation that describes the two rules Friction Friction: This is the force that always opposes motion. Three Types of Friction Static Friction: Friction between two surfaces that are not moving Rolling Friction: Friction between rolling object and a flat surface(least amount of friction Sliding Friction: Friction between flat surfaces where there is some movement but force must be constantly applied Newtons Second Law Description F = 1000 x N =

5 Newtons Third Law Short: Action/ Reaction Long: For every action force there is an equal and opposite reaction force Example: A NASA rocket shoots explosive gases into the ground… the group pushes back with the same force(based on mass and acceleration) and the rocket exits the earth More examples: 1.Breaking hand by punchingBreaking hand by punching someone in the face 2.Any propulsion device 3 rd Law Poster

6 PersonMass (kg) Mass= Weight/ 9.8 Initial Force This is also the weight Mass x gravity Final Force(Final F –Initial F) Jumping ForceJumping Acceleration (m/s/s) A= Force/Mass

7 Gravity Gravity: A force of attraction between two objects Big objects Big objects attract little objects to them: Big objects Big objects attract little objects to them: TimeSpeed (m/s)AccelerationDistance covered 1 s 10 2 s s s s s The average skydiver hits his terminal velocity at a speed of 56 m/sskydiver The average skydiver hits his terminal velocity at a speed of 56 m/sskydiver Terminal velocity: highest velocity a falling object can reach due to force air resistance = force gravity Terminal velocity: highest velocity a falling object can reach due to force air resistance = force gravity When an object is in free fall it is no longer accelerating ALL OBJECTS FALL AT THE SAME SPEED TOWARDS THE EARTH BUT SOME ARE AFFECTED MORE BY AIR. Why does a feather fall at a different speed than a hammer on earth but not on the moon? There is no air resistance on the moon! Projectile Motion Weight:Weight: The effect of gravity on an object Weight: Weight = Mass x gravity Weight:Weight: The effect of gravity on an object Weight: Weight = Mass x gravity MassWeight Belongs to an object( always the same) Changes depending on the planet or moon What if one object object is shot horizontally and another is dropped? The only force acting on either ball is GRAVITY so they fall at the same rate and hit the ground at the same time

8 1. At the same speed, which of the following has the greatest inertia? a. 1 kg b. 2 kg c. 5 kg d.10 kg 2. What will happen to an object when a net force acts on it? a. Fall B. Stop C. Accelerate D. Go in a circle 3. According to Newton's 2nd law if you double the mass of an object and push with a constant force then the acceleration of that object will be a. halved b. unchanged c. doubled d. tripled 4. Two forces of 6 N and 3 N act upon an object in opposite directions. What is the net force acting on the object? (See image below) a. 3 N to the left b. 3 N to the right c. 9 N to the left d. 9 N to the right 5.A truck with a mass of 1000 kg hits a wall and unloads a force of 400,000 newtons. What is the negative acceleration of the trucks?. a m/s 2 b m/s 2 c m/s 2 d m/s 2 WARMUP QUIZ


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