The Basics
What are the two main types of drag
Water resistance and air resistance.
Look at Photo A. Why do the crates need parachutes with a large surface area?
To produce a lot of drag and slow their fall
As a vehicle goes faster and faster, what happens to the amount of drag?
The drag increases.
Which fluid is more dense and harder to push through: Air or Water?
Water.
Drag is partly caused by this force, which happens when an object rubs against a fluid.
Drag is partly caused by this force, which happens when an object rubs against a fluid.
What is the specific name for a shape that makes it easier for fluid to move around an object?
Streamlined.
When the drag force is exactly the same size as the engine's forward force, the forces are said to be ______.
Balanced
If a car designer wants to increase a car’s top speed without changing the engine, what should they do to the car's shape?
Make it more streamlined/reduce the surface area facing forward.
True or False: Drag is a force that speeds up moving objects.
False (It is a resistance force that slows things down).
Look at Photo B and C. Which vessel is built for speed, and which is built for slow exploration?
B (Submarine) is for speed; C (Alvin) is for exploration
Why do objects (like space shuttles or fast cars) heat up as they move through the air?
Friction between the object and the air particles.
If a vehicle is traveling at a steady speed, what can you say about the relationship between the engine force and the drag force?
They are equal/balanced
According to the "Fact" box, what do golf balls have on their surface to reduce drag?
Small dimples.
Name two ways the cyclist in Photo E has reduced his drag.
Wearing a smooth/tight suit, using a teardrop-shaped helmet, or crouching low.
(Hard!) Use "particles" to explain why drag is lower when an object moves slowly.
The object has to push fewer fluid particles out of the way every second.
A parachute opens while a skydiver is falling. What happens to the drag force and the speed of the skydiver?
Drag increases and the skydiver slows down.
This resistive force, often called air resistance when involving planes, opposes the motion of an object through a fluid.
drag
A larger, faster aircraft like the Hercules requires more of this from its engines to overcome the increased drag of its size.
thrust (or force)
Unlike most substances, this compound actually becomes less dense when it freezes into a solid.
water (or ice)
Melting ice is considered this type of change
physical change