Mass the amount of matter in an object. Mass of an object is constant throughout the universe

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2 Mass the amount of matter in an object. Mass of an object is constant throughout the universe Weight is a force, it is the measure of how strong gravity pulls on that matter.

3 A force that produces no change in an object s motion because it is balanced by an equal yet opposite force. Unbalanced forces are forces that result in an object s motion being changed.

4 Forces can create changes in motion (acceleration or deceleration). Acceleration is when the motion of an object changes. Examples: speed up, slow down, or change direction. Motion can be described as change in an object s position.

5 1st Laws States that an object at rest will remain at rest and an object in motion will remain in motion, unless an outside force acts on it (such as friction). This law is also called the LAW OF INERTIA. Inertia is the resistance of any physical object to any change in its state of motion.

6 EXAMPLE Imagine a dog sitting in the passenger seat of a car. Suddenly, the brakes are slammed to avoid the bozo driving in front. What happens to the sweet dog? She goes flying into the dashboard! Poor puppy experienced inertia! Even though the car was stopped by the force of the brakes/friction, she kept going. A dog in motion remains in motion!

7 Or what happens to your dog when you suddenly slam on the gas pedal? EXAMPLE

8 INERTIA The bowling ball. A bowling ball has more inertia than a golf ball. The greater an object s inertia, the greater the force needed to change its motion. Inertia comes from mass. Objects with more mass have more inertia and are more resistant to changes in their motion

9 EXAMPLES What about space? Have you ever noticed astronauts tools seem to float? They can just place them in space and they stay in one place. There are very few forces acting on objects in space. Gravity however is still a force in space. Astronauts are falling, but nothing stops them, so they appear weightless.

10 2 nd Law States that a force on an object will move the object in the direction of the force. The relationship between force, mass and acceleration is summarized by the formula: Ex. This law explains why a golf ball will roll in the direction of a force applied to it. Describes the motion of objects when unbalanced forces act on the object

11 Bigger mass.the less acceleration

12 (A) 0.2 N (B) 0.8 N (C) 1.5 N (D) 6.0 N Q: The frog leaps from its resting position at the lake s bank onto a lily pad. If the frog has a mass of 0.5 kg and the acceleration of the leap is 3 m/s 2, what is the force the frog exerts on the lake s bank when leaping? Formula chart says F=ma, m is mass in kg, a is acceleration in m/s 2. So,.5 kg x 3 m/s 2 = 1.5 N

13 Newton s second law of motion can be used to calculate acceleration. For example, suppose you pull a 10-kg sled so that the net force on the sled is 5 N. Rearrange the formula The acceleration can be found as follows:

14 When you spin a bucket of water over your head without spilling a drop, you are also applying a centripetal force. If you let go of the bucket, it will move in a straight line.

15 3 rd Law States that for every action there is an equal but opposite action. Ex. A skater pushes back on the skates but the skater moves forward. There are two forces resulting from this interaction. Action - Reaction

16 Can explain the motion if almost any object (animals included) Forces work together (not independent of one another) Can use the laws to make predictions about motion Spacecraft: can predict where Mars will be at the time a spacecraft reaches is, and can control the force on the spacecraft to arrive at the right place/time.

17 Formal definition: a force that acts on a object moving in a circular path and pushes or pulls the object toward the center of the circle.

18 If you are constantly accelerating, there must be a force acting on you the entire time. The force exerted is the centripetal force and always points toward the center of the circle. In circular motion the centripetal force is always perpendicular to the motion.

19 Centripetal force keeps the planets in orbit. According to Newton s 1st law, all masses have inertia and would like to move at constant speed in a straight line. Earth wants to move straight but it is prevented from doing so due to the sun s gravity. The sun applies a centripetal force.