PS+5+-+5th+Period+Brown

=__Force and motion__= Key concepts:Basics of Motion Motion- occurs when an object changes its position Reference point- allow us to determine wether an object has moved Relative motion- you ar emoving relative to the things around you Distance- describes how far an object has moved (total amount measured in meters of how far an object has traveled) Displacement- is both the distance and direction that has changed from a starting point ( both the distance and direction) Speed- to find speed you must measure two quantities: distance traveled and time/ speed is measured in meter/seconds Instantaneous speed- the speed being traveled at that moment Average speed- calculates distance over time (speed=D/T).

**Forces: Intro to Forces**
Force-a force is a push or pull that one body exerts on another. Balanced force-When two things are applying an equal force on an object, then the force is balanced. Unbalanced force-When two things aren't applying equal force on an object, then the force is unbalanced. Net force-when two or more forces act on an object at the same time, the forces combine to createthe net force. Inertia-the tendancy of an object to resist any change in its motion. Mass-the amount of matter in an object. Law of Inertia (Newton's First Law)- an object moving at a constant velocity keeps moving at a constant velocity unless a force acts on it.

**Newton's second law-**
Acceleration- how something speeds up over time. Newton's second law- describes how force, mass, and acceleration are connected. F=ma- Force= mass* acceleration. Friction- the force that opposes motion between two surfacesthat are touching eachother.(static, rolling, sliding, Terminal Velocity, and Air Resistance.) Static- the friction between two surfaces that are not moving past eachother. Rolling- the friction between a rolling object and the surface it rools on. Sliding- the force that opposes motion of 2 surfaces sliding past eachother. Terminal Velocity- the highest velocity that a falling object will reach. Air Resistance-the resistance force to gravity.

**Gravity-**
Law of Gravitation- anything that has mass is attracted by the force of gravity. Distance- the difference of space between two objects. Gravitational Force- the larger mass of an object, the greater the force. Gravity - is a long range force Weight - gravitational force exerted on an object. Projectile Motion - the motion of anything that is shot or thrown out into the air.

** Newton's Third Law- **
Centrepital Force -acceleration towards the center of a curved or circular path. Newton's Third Law - " for every action of force, there is and equal and opposite reaction force." Momentum - an impelling force or strength.

**Universal Gravitation-**
Newton's law of Universal Gravitation -there is a force of attraction between all objects in the universe. Attractive force **-** the greater mass of an object, the greater the attractive force is.

1. What is weight? a. Gravitational force b. **Electromagnetic force** c. Strong nuclear force d. Weak nuclear force
 * 1) Which of the following is a force that can oppose of change in motion?
 * 1) Gravity
 * 2) Air resistance
 * 3) ** Friction **
 * 4) All of the above
 * 1) ** The force an object exerts due to gravity **
 * 2) The mass of an object
 * 3) The acceleration of gravity
 * 4) All of the above
 * 1) Which force is responsible for static electricity?


 * 1) What is the value of earth’s free-fall acceleration?
 * 1) 6.67 m/s
 * 2) 6.67*10 N m/kg
 * 3) ** 9.81 m/s **
 * 4) 9.81 N m/kg
 * 1) A passenger in a car that suddenly stops will
 * 1) ** Lean Forward **
 * 2) Lean Backward
 * 3) Lean to the right
 * 4) Feel no motion
 * 1) A ___ is the unit of force
 * 1) **Newton**
 * 2) Joule
 * 3) Kelvin
 * 4) Ampere
 * 1) Velocity includes both speed and
 * 1) Distance
 * 2) Rate of change
 * 3) Time
 * 4) Direction
 * 1) Identify what a person will feel when they are in a car that is accelerating very rapidly in a straight line on a flat road
 * 1) Pushed up out of seat
 * 2) ** Pushed back into a seat **
 * 3) Pushed down unto seat
 * 4) Pushed forward out of seat
 * 1) Which surface will exert the most friction on a ball?
 * 1) Grass
 * 2) ** Concrete **
 * 3) Glass
 * 4) Gravel
 * 1) An object is taken from the earth to that moon. Identify the statement that describes the mass and weight of the object ob the moon compared to its mass and weight on earth.
 * 1) Mass is the same and weight is the same on the moon
 * 2) Mass is greater and weight is greater on the moon.
 * 3) ** Mass is the same and weight is less on the moon. **
 * 4) Mass is less and weight is less on the moon
 * 1) A book lying on your desk will only move if
 * 1) ** An unbalanced force acts on it **
 * 2) A downward force acts on it
 * 3) A normal force acts on it
 * 4) The frictional force on it is reduced
 * 1) Mariah and Charley each pull at opposite ends of a rope. Charley is stronger. Who will move the backwards?
 * 1) The rope will move Mariah and Charley wont.
 * 2) Both Mariah and charley will move backwards
 * 3) Mariah will move backwards
 * 4) ** Charley will move backwards **
 * 1) Calculate the average speed of a bicyclist who travels 21 miles in 90 minutes.
 * 1) .25 mph
 * 2) ** 4 mph **
 * 3) 10 mph
 * 4) 15 mph
 * 1) A car engine works harder to accelerate from 0 to 10 km/hr than it does to maintain a 10km/hr velocity. Why?
 * 1) ** Because static friction is harder to overcome than kinetic or rolling friction **
 * 2) Because static friction is easier to overcome than kinetic or rolling friction
 * 3) Because static friction is harder to overcome than potential friction
 * 4) Because static friction is easier to overcome than potential friction
 * 1) Identify changes in force and mass that together produce an increase in acceleration.
 * 1) ** Increased force and mass **
 * 2) Increased force and decreased mass
 * 3) Decreased force and increased mass
 * 4) Decreased force and decreased mass

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