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? Distance = speed x time If I drove 3 m/s for 10 seconds, how far have I gone? 3m/s X 10 s = 30 m

What changes motion? Force!! F = mass x acceleration 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 by a moving object per unit of time. Speed affect the energy of an object. The faster it moves, the more kinetic energy it has. Speed = distance time

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. 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 1500 km/s 65 m/s north 3000 km/s Velocity Speed Velocity Speed

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

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 = m/s = 7.5 m/s^2 8.0s

Friction Friction is a force that opposes motion. 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. Momentum = mass x velocity

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- is the term used to describe 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/s 2.

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