Understanding Force and Motion

• Force is a push or pull on an object.
• Motion is a change in position relative to a reference point.
• Speed is distance divided by time.
• Velocity is speed with a direction.
• Acceleration is a change in speed or direction.
• Friction is a force that opposes motion between two surfaces in contact, due to their roughness.
• Gravity is the force of attraction between objects due to their mass.
• The Universal Law of Gravity: All objects experience gravity; greater mass means greater gravitational force, and greater distance means smaller gravitational force.
• A Newton is a unit of force.
• A reference point is an object that appears to stay in place.
• Potential energy is stored energy or the energy of position.
• Kinetic energy is the energy of motion.
• Mass measures the amount of matter, while weight measures the gravitational pull on an object.
• Air resistance is friction with the air.
• Terminal velocity is the maximum velocity, occurring when the force of gravity equals air resistance.
• A speedometer reading of 49 mph indicates instantaneous/current velocity.
• The ground/mountain can be used as a reference point to determine if a balloon is in motion.
• The velocity of a baseball thrown 38 meters from third base to first base in 2.1 seconds is 18 m/s toward first base.
• A diagram showing forces results in a net force of 30 N to the left.
• A cyclist would travel 44 km in 4 hours at a velocity of 11 km/hr.
• Given a diagram, you can calculate the distance to be 20cm.
• A car increasing its velocity from 0.4 m/s to 4.7 m/s in 3.9 seconds has an acceleration of 1.1 m/s².
• A car traveling north with a velocity of 40 m/s slowing down to 25 m/s in 8 seconds has an acceleration of -1.9 m/s².
• A bowling ball dropped from the top of a building takes 4.5 seconds to hit the ground, resulting in a velocity of 44.1 m/s upon impact.
• A baseball dropped from a balcony takes 2.5 seconds to hit the ground, giving it a velocity of 25 m/s at impact.
• If a bowling ball, baseball, and feather are dropped from the same height, the feather falls slowest due to greater air resistance.

Data Table Analysis

• After 6 hours, an object has traveled 25 km.
• An object travels 16 km in 4.0 hours.
• The average speed of an object during the 3 to 4 hour time interval is 1 km/hr.
• The average speed of an object during the 6 to 8 hour time interval is 4.5 km/hr.
• The average speed of an object for the entire 10-hour time interval is 3.9 km/hr.
• During the 8 to 9 hour time interval, the object is stopped.

Acceleration Calculations from Graph

• Calculate the acceleration from 0 s to 2 s equals 7.5 m/s².
• Calculate the acceleration from 2 s to 5 s equals 1.7 m/s².
• Calculate the acceleration from 5 s to 7 s equals 10 m/s².
• Calculate the acceleration from 7 s to 10 s equals 0 m/s².
• The greatest acceleration occurs during the time interval of 5 to 7 seconds.

Motion Analysis Graphs

• Acceleration is negative during time interval C.
• Acceleration is positive during time interval A.
• Velocity is constant during time interval B.

Motion Descriptions from Speed Graphs

• The motion represented accelerating.
• The motion represented deceleration or negative acceleration.
• The motion represented constant speed.
• The motion represented as STOPPED.