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 masses.
• The Universal Law of Gravity states all objects experience gravity, with greater mass leading to greater gravitational force, and greater distance leading to 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.
• Motion of a balloon can be determined using the ground/mountain as the reference point.
• 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 with forces resulting in a net force of 30 N to the left.
• A cyclist travels 44 km in 4 hours at a velocity of 11 km/hr.
• Distance calculation is given by the the equation d = vt
• An object that travels 10 cm is proportional to an object traveling 20 cm given the same time and velocity.
• 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 a building takes 4.5 seconds to hit the ground and achieves a velocity of 44.1 m/s.
• A baseball dropped from a balcony takes 2.5 seconds to hit the ground, reaching a velocity of 25 m/s.
• When dropping a bowling ball, baseball, and feather from the same height, the feather falls slowest due to greater air resistance.
• After 6 hours, an object has traveled a distance of 25 km.
• An object travels 16 km in 4.0 hours.
• An object's average speed during the 3 to 4 hour time interval is 1 km/hr.
• An object's average speed during the 6 to 8 hour time interval is 4.5 km/hr.
• An object's average speed for the entire 10 hour time interval is 3.9 km/hr.
• An object's motion during the 8 to 9 hour time interval shows the object stopped.

Acceleration Calculations from a Graph

• The acceleration from 0 s to 2 s calculates to 7.5 m/s².
• The acceleration from 2 s to 5 s calculates to 1.7 m/s².
• The acceleration from 5 s to 7 s calculates to 10 m/s².
• The acceleration from 7 s to 10 s calculates to 0 m/s².
• Acceleration is greatest during the 5 to 7 seconds interval.

Motion Analysis from Graphs (Speed vs. Time)

• Time interval C demonstrates negative acceleration.
• Time interval A demonstrates positive acceleration.
• Time interval B demonstrates constant velocity.
• Graph e illustrates acceleration.
• Graph f illustrates deceleration or negative acceleration.
• Graph g illustrates constant speed.
• Graph h illustrates the object stopped.