Drag

• Revision can be a bit of a drag, but hey, you're over halfway through the topic now
• No use slowing down now-however, there's quite a bit of that on this page
• Friction


  Always there to slow things down
• If an object has no force propelling it along

  It will always slow down and stop because of friction (unless you're in space where there's nothing to rub against)
• Friction always acts in the opposite direction to movement
• To travel at a steady speed

  The driving force needs to balance the frictional forces
• Friction


  You get it between two surfaces in contact, or when an object passes through a fluid (drag)
• Drag


  The resistance you get in a fluid (a gas or a liquid)
• Air resistance


  A type of drag- it's the frictional force produced by the air acting on a moving object
• Streamlined shape


  • The most important factor by far in reducing drag
  • Allows fluid to flow easily across it, reducing drag
• Parachutes work in the opposite way - they want as much drag as they can get
• Frictional forces from fluids

  Always increase with speed
• A car travelling at 70 mph

  Has much more friction to work against compared to 30 mph
• At 70 mph


  The engine has to work much harder just to maintain a steady speed