Topic 5 Flashcards
What is a vector quantity
+ examples
Has a magnitude and a direction
Force ,velocity , displacement , acceleration
What is a scalar quantity
+examples
Has only magnitude no direction
Speed ,distance, mass , temperature , time
Examples of contact forces
Friction , air resistance , tension
Examples of non contact forces
Magnetic force , gravitational force , electrostatic force
What are gravity’s important effects
Gives everything a weight
Makes things fall toward the ground
What is weight
The force acting on an object due to gravity
Measure in newtons
What is a resultant force
The overall force acting on an object
What happens when a force moves an object through a distance
Work is done and energy is transferred
How to we draw a scale diagram of forces in equilibrium
The tip of the last force you draw should end at the tail of the first force you drew begins
What does the equation force = ke also work for
Compression - the extension is the difference between the natural and compressed lengths
What is the limit of proportionality
The Max force that a spring can take before extension is no longer directly proportional to force
Investigating springs practical
- Measure natural length of spring with ruler clamped to stand - take reading at eye level (add a marker eg tape) to the bottom of the spring to make it more accurate
- Add mass to spring and allow it to come to rest
- Record the mass and the new length of the spring - record the extension (change in length)
- Repeat until you have enough measurements (6+)
- Plot on a graph - it will curve when the limit of proportionality is exceeded
What is a moment
The turning effect of a force
To get the max moment you must push at right angles
What do levers do
Increase the distance form the pivot so less force is needed to get the same moment
Examples of levers
Long stick , wheelbarrow
What are gears
Circular disks with teeth that interlock with other gears.
They are used to transmit rotational force
Larger - bigger moment, slower
Smaller - smaller moment , faster
What is upthrust
The resultant force cause by different amounts of pressure acting on different parts of a submerged object
It is equal to the weight of fluid that has been displaced by an object
When/how does an object float
When upthrust = the objects weight
Whether or not an object will float depends on density
Less dense(than fluid) - floats
More dense (than fluid)- doesn’t
What is the atmosphere
A thin layer of air that surrounds the earth (thin compared to size of earth)