Motion

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

Distance How can I find out how far I’ve gone?

What changes motion? Force!! A force is a push or pull that can change motion A force can move an object A force can transfer energy to an object 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. Like tug of war…the winners are pulling the other team with more force; therefore the pulling forces are unbalanced.

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

Speed We talk about speed everyday. Speed is the distance traveled in a unit of time. Speed affect the energy of an object. The faster it moves, the more kinetic energy it has. Speed = distance Avg. Speed= d2-d1 time t2-t1

Kinetic Energy – Energy of Motion Speed and mass affect the kinetic energy of an object. 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. Greater mass=more kinetic energy The more mass in an object, the more force needed to move it.

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

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

Acceleration Acceleration is the rate of change in velocity.

Friction Friction is a force that opposes motion between two surfaces that are touching. Can be caused by wind, water, surface texture, etc.

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

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

Sir Isaac Newton 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 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- the tendency of an object to remain in motion or stay at rest.

Newton’s Second Law Motion produced by unbalanced forces. The units of force are “Newtons” 1 N = 1 kg x m/s s 1N is the force on a 1kg mass that will accelerate that mass at 1 m/s2.

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