Brittany Moore 8/29/12

motion: movement What two things are important in describing motion: Distance Time Do you have to see something literally move to know its in motion?

Distance: how far something has moved Meters (m), kilometers (km) Displacement: distance and direction of an object’s change in position from the starting point What are the differences between distance and displacement?

Speed: distance an object travels per unit of time How do we calculate speed? Speed = distance/time Ex: A car traveling at a constant speed covers a distance of 750 m in 25 s. What is the cars speed?

A passenger elevator travels from the first floor to the 60 th floor, a distance of 210 m, in 35 s. What is the elevators speed? A motorcycle is moving at a constant speed of 40km/h. How long does it take the motorcycle to travel a distance of 10km?

Does your car always run at a constant speed? What might a graph of your car’s speed look like on a typical day to school?

Average speed: total distance traveled divided by the total time of travel Ex: A runner travels 100 m in 30 s. What is their average speed? Instantaneous speed: speed at a given point of time Ex: On my way to school I look down to see that I am travelling km!

What kind of graph would be best to show motion? Distance over an amount of time… How does the steepness of a line effect the speed? Speed = slope

Lets have a race…can you calculate your speed? Speed = distance / time = m / s Work in groups to complete worksheet.

Velocity: speed of an object and the direction of its motion The velocity of an object can change even if the speed of the object stays the same Ex: BMS—the race car has a constant speed and is going around an oval track; even though the speed remains constant, the velocity changes because the direction of the car’s motion is changing constantly

Acceleration: the rate of change of velocity Acceleration occurs when an object changes its speed, direction, or both. Change in velocity = final velocity – initial velocity Acceleration = V f – V iUnits in m/s 2 t Ex: Speeding up and slowing down. As a car speeds up: positive velocity, acceleration, and speed. As a car brakes: positive velocity, negative acceleration (deceleration) and decreasing speed.

Don’t athletes have to make quick changes in acceleration? Can you think of any equipment used by athletes to help with this? Yes! Examples include: -starting blocks for runners -cleats on shoes -rubber soled shoes -special clothing

Force: push or pull on an object; changes in the movement Ex: hitting a tennis ball, gravity on your body, pool, etc. Force = mass x acceleration

Net force: when two or more forces act on an object at the same time Balanced: equal forces acting in opposite direction Unbalanced: unequal forces acting in opposite direction