Motion What is motion anyway Motion is a

Motion

What is motion anyway? Motion is a change in position, measured by distance and time. n Anything moving is in motion. n

Distance How can I find out how far I’ve gone? n Distance = speed x time n If I drove 3 m/s for 10 seconds, how far have I gone? n 3 m/s X 10 s = 30 m

What changes motion? Force!! F = mass x acceleration n A force is a push or pull that can change motion n A force can move an object A force can transfer energy to an object n For example, pushing on a wall doesn’t move the wall, but energy is being transferred.

Unbalanced Forces In order for a force to move an object, there must be unbalanced forces. n Like tug of war…the winners are pulling the other team with more force; therefore the pulling forces are unbalanced. n

How can force affect motion? Resistance forces (friction or wind) that oppose motion can slow down motion. n A force in the same direction can speed up motion. n

Speed We talk about speed everyday. n Speed is the distance traveled by a moving object per unit of time. n Speed affect the energy of an object. The faster it moves, the more kinetic energy it has. n Speed = distance time n

Kinetic Energy – Energy of Motion Speed and mass affect the kinetic energy of an object. n If two objects are moving at the same speed, but one object has a greater mass, then the object with the greater mass will have more kinetic energy. n The more mass in an object, the more force needed to move it. n

Velocity and Speed are like fraternal twins- very similar, but with important differences. n Velocity is speed in a given direction. n n n 35 mph NORTH 4 km/sec EAST

Which is which? 100 m/s right n 1500 km/s n 65 m/s north n 3000 km/s n Velocity Speed

Acceleration n Acceleration is the rate of change in speed. Acceleration = Change in speed (m/s) Time (s) n Example: 0 to 60 mph in 3 s n

Example The race car accelerated from stop to 60 m/s by the finish line. It took the racecar 8. 0 seconds to finish. What was the acceleration? Original speed = 0, Final speed = 60 m/s, Time = 8. 0 seconds Acceleration = 60 - 0 m/s = 7. 5 m/s^2 8. 0 s

Friction is a force that opposes motion. n Can be caused by wind, water, surface texture, etc. n

Resistance Force Have you ever ridden down the street on your bike and felt the wind push against you? n That’s air resistance! n Air resistance is the frictional force from the air that resists forward motion n

Momentum is the property that a moving object has because of its mass and velocity. n All moving objects have momentum. n n Momentum = mass x velocity

Sir Isaac Newton n Isaac is famous for his discovery of gravity. He is also known for his three laws that explain all aspects of motion.

Newton’s First Law n An object at rest will remain at rest, and a moving object will remain at a constant velocity unless unbalanced forces act on it. ** Inertia- is the term used to describe the tendency of an object to remain in motion or stay at rest.

Newton’s Second Law n Motion produced by unbalanced forces. n The units of force are “Newtons” 1 N = 1 kg x m/s s 1 N is the force on a 1 kg mass that will accelerate that mass at 1 m/s 2. n

Newton’s Third Law n For every action, there is an equal and opposite reaction.