Matter in Motion

Motion Motion is an object’s change in position relative to a reference point. A reference point or frame of reference is how to tell if something is moving or not. It is a place or object one assumes is fixed. What does fixed mean? What do we use as frames of reference here on Earth? Things found on the surface such as trees, buildings, mountains, etc. What about space?

Speed The distance an object travels in a certain amount of time. Distance (D) Speed (s)= Time (t) SI Units for speed is meters per second or m/s

Other speed formulas Distance = speed x time Distance Time = Speed

What is the difference between Velocity speed AND direction What is the difference between this picture and this picture?

Constant vs. Average Speed Equal distances are covered in equal amounts of time D (m) t (s) D (m) Total D Average Speed = Total t t (s)

Acceleration The rate at which velocity changes Final velocity (v) - Starting velocity (v) Acceleration = change in time Positive acceleration is when an object is increasing in velocity Negative acceleration is when an object is decreasing in velocity Centripetal acceleration occurs when an object is turning or moving in a circle

Force A push or a pull that stops, starts, or changes the direction of an object SI unit = Newton (N) It transfers energy to an object. Mass and acceleration are used to determine the amount of force

Named after Sir Isaac Newton A newton is the amount of force needed to move a 1Kg object at an acceleration rate of 1m/s2 N = 1Kg x 1m/s2

Balanced vs. Unbalanced Net Force - all the forces acting on an object. Same direction add together. Different direction subtract Balanced forces produce a net force of zero. Is the object moving? NO!!

Unbalanced forces occur when the net force does not equal zero http://newsimg.bbc.co.uk/media/images/43062000/jpg/_43062057_montage_motion.jpg Necessary for a nonmoving object to start moving.

An opposing force as two objects pass by each other. Friction An opposing force as two objects pass by each other. Two forces that effect the amount of friction are: the force pushing the surfaces together and the roughness of the surfaces.

Friction Types Sliding Friction: two surfaces slide over each other. The weight and the surface are two important factors: More weight more friction Rolling Friction: An object that rolls over a surface. Which requires more force to be applied? Rolling or sliding friction?

Fluid Friction: Occurs between an object and a fluid such as water, oil, and air. Friction Control: Ways to reduce the amount of friction that occurs between moving parts.

Universal Forces Gravitational Force Weakest of the forces It’s strength depends on the amount of mass of the objects and the distance between them Acts on all matter Law of Universal Gravitation Sir Isaac Newton Every object in the universe attracts every other object Keeps planets in orbit around sun Moon and Earth system affects our tides

Electromagnetic Force Two different forces that are closely related. What are they? Electric - acts on charged particles called ions. Much stronger than gravitational force. Ranges from static cling to lightning. Attracts and repels. Magnetic - occurs with magnets. Magnetic domains line up within the magnetized object. Only cobalt, iron, and nickel can become magnetic. Also attract and repel.

Nuclear Forces are the forces that hold particles together in the nucleus of the atom. Two kinds: Strong nuclear and weak nuclear. 1. Strong nuclear The strong force is what holds quarks together in the nucleus. Quarks make up protons and neutrons so it is a short distance. When the bonds are broken, a HUGE amount of energy is released. Is used for electricity to atomic bombs. 2. Weak nuclear Holds protons and neutrons together. Neutrons decay to form new neutrons which causes radioactive decay. Allows for carbon dating. Also causes fallout after a nuclear reaction.

Weight vs. Mass Review Weight is the measure of the gravitational force on an object. Mass is the amount of matter that an object contains. Weight is going to vary with the pull of gravity. Where will we weigh more, the Earth or the moon? Will our mass change? Mass is measured in grams and weight is measured in newtons.