Speed, Velocity, and Acceleration

Motion What is Motion? Motion is a change in position.

Speed What is Speed? Speed is a Rate of Motion. Types of Speed: A measurement of how fast the motion took place. Types of Speed: 1) Instantaneous Speed 2) Constant Speed 3) Average Speed

Instantaneous Speed This is the rate of motion at any given point of time. Example: The speedometer of cars.

Constant Speed A speed that does not vary. Example: Cruise control in cars. Set cruise at 55 mph on long trips and your car will stay at 55 mph.

Average Speed An Average of all of the instantaneous speeds gathered over a period of time. In other words: If a drive from here to Disney World takes 15 hrs & 40 min at 65mph, Are you traveling 65mph for the whole trip?

Distance Velocity (SPEED) = Time V = V = Speed Formula Example: What is the Average speed if a car travels 200 miles in 4 hours? 200 mile = 4 hour V 50 mile = hour

Velocity What is Velocity? Velocity is the rate of motion in a specific direction. (Speed and Direction) If either speed or direction change, then VELOCITY changes.

Did Velocity Change? A car is traveling west on route 22 at 45 mph. When it approaches the light at sheets, it slows to 5 mph. Did Velocity change? YES: The Speed changed but direction stayed the same.

Did Velocity Change? A ball is thrown against a wall at 25 mph and bounces back to the person at the 25 mph. Did Velocity change? YES: The Direction changed but speed stayed the same.

Velocity Acceleration = Time Acceleration What is Acceleration? Acceleration is the rate of change of Velocity. Final Velocity – Initial Velocity Velocity Acceleration = Time

V A = = = T meters second m s2 m s s Standard SI Units x 1 Velocity & Speed: Can be measured with any distance over any time, but the SI standard is: meters second Acceleration: meters per Second Squared m s2 V m s A = = 1 s x = T

Every object in motion requires ENERGY There are several different forms of energy: Kinetic Energy: is energy due to motion KE = ½ Mass x Speed2 (Measured in joules) Mass of the car & people = 2000 kg Speed on the 1st hill= 30 m s What is the Kinetic Energy?

Kinetic ENERGY Example: KE = ½ Mass x Speed2 KE = 0.5 x 2000 kg x (30 )2 M S KE = 1000 kg x 900 M2 S2 KE = 900,000 joules This is the same amount of energy that is used to light FOUR 60 watt light bulbs for one hour.

Some objects at rest also have ENERGY Potential Energy: is energy that is stored due to the interactions between objects (Elastic PE, Chemical PE, or Gravitational PE) GPE = Mass x Gravity x Height (Measured in joules) Mass of car & people = 3000 kg Height of 1st hill = 21 m Gravity Constant = 9.8 m S2 What is the Potential Energy?

Potential ENERGY Example: GPE = Mass x Gravity x Height GPE = 3000 kg x 9.8 m x 21 m S2 GPE = 617,400 joules This is the same amount of energy that is used to light ONE 100 watt light bulbs for two hour.