Forces Gravity and Newton's 2nd Law

Mass = how much matter is in an object More mass = greater inertia (harder to move or stop)

Newton's Second Law of Motion the acceleration of an object is in the same direction as the net force on the object and can be calculated with this equation: Or simply F = ma

Practice: 1. If you push an object that has a mass of 2 kg, and the net force acting on the object is 6N, what is the object's acceleration? F = ma or a = f/m 2. If a mass of 5kg is moving at an acceleration of 3 m/s 2, what is the force?

More Practice 1. If a toy helicopter has a mass of 30kg, and the net force on it is 150 N, what is the helicopter's acceleration? 2. A boat being pulled by a truck has an acceleration of 2 m/s 2.The boat's mass is 1000kg. What is the force pulling the boat? 3. A block is being pushed with a force of 20N and it has a mass of 5 kg. How fast is the block accelerating?

Friction = a force that opposes the sliding motion between two objects images by photoeverywhere.co.uk It keeps these cars from sliding down the hill.

The amount of fiction depends on the surfaces and the force pressing the surfaces together. An icy surface has less friction than a dry surface. Why does putting sandbags in your trunk help you to not slide on the ice?

Static Friction is what prevents two surfaces from sliding past each other. Ex. You push a large box, but it just won't move See Simpsons Ice Skating Video Sliding Friction i s the forces that opposes two surfaces that are already sliding. Ex. Once you get the box moving, it is easier to slide.

Air Resistance = a friction like force that affects objects that move through the air The feather has more air resistance, so it falls slower than the elephant. Normally, objects fall at the same speed. ary/module_viewer.php?mid =118&l=

If you jump out of a plane, you might want to use a parachute. When you first jump out a plane, gravity is the force acting upon you (with some air resistance). Eventually, the force of the air resistance and gravity is equal and you no longer accelerate - this is called the TERMINAL VELOCITY

Gravity = the attractive force between two objects; depends on mass and distance Law of Universal Gravitation. Fg = Force of Gravity M = mass1 m = mass 2 d = distance G = a constant If the objects move farther apart, the force between them will [increase / decrease / stay same ]

1. What force pulls the apple down? _____________ 2. Force = _______________ x _______________ 3. The rate of acceleration on earth is _________ m/s2 ______________= the gravitational force exerted on an object ________________= the amount of matter in an object _________________remains constant, while _____________________________is dependent upon gravity. FORCE is measured in ______________________

Weight depends on gravity, which can vary depending on the planet. The force of gravity on the moon is 1.6 m/s 2 So, you would actually weigh less on the moon than you weigh on earth.

Weightlessness & Free Fall When an object appears to be floating, like the astronauts in space, it is because the force of gravity isn't as strong, so they *feel* weightless. Astronauts still have mass, and in actuality, gravity is still acting upon them, they are just falling *around* the earth, not straight down. Check out this animation of an orbiting cannonballorbiting cannonball

Elevator Physics When you travel in an elevator, the force acting upon you varies depending on whether you are going up and down. For a very short period, you will be "weightless" as the elevator's acceleration is equal to the acceleration of gravity. If you stand on a scale while an elevator moves: As it moves upwards, your weight will increase As it goes down, weight decreases At free fall, weight = 0

Projectile Motion Imagine two balls on top of a building. One is dropped and the other is thrown. Which one lands first?_________________ The thrown ball has both horizontal and vertical motion, and the dropped ball has only vertical motion..

CENTRIPETAL FORCE = acceleration toward the center of a curved path; as an object goes around a curve, it accelerates, producing a force The force depends on mass, velocity and the radius of the circle. Roller coaster goes around a loop but the car (and people) don't fall You can spin a bucket full of water around your head without losing the water

When you are in a car turning, you feel like you’re being pushed toward the outside of the turn. So why does it FEEL like you’re being pushed. Because of _______________________________ Your body wants to continue on its original path as the car turns, you will continue to move straight. What Law is this? _______________

QUIZ - NEWTON'S LAWS

1. Write the equation used to calculate FORCE (F). 2. Use that equation to calculate the force of an object traveling at 10 m/s 2 and having a mass of 5kg. 3. Name the force that opposes two objects sliding against each other: _______________ 4. A skydiver reaches terminal velocity when the force of air resistance is equal to ___________

5. Mass is how much _________________is in an object 6. If you are on an elevator, and your weight is 0, you are in _________________ fall. 7. Weight = ________________ x gravity 8. What is the force that causes acceleration around a curve?________ 9. What is the force of gravity on the moon? ____ REVIEW: How does mass affect inertia??