1 Forces and shape Flashcards
What are the types of forces?
- Gravitational (weight)
- Electrostatic
- Thrust
- Upthrust
- Air resistance (drag)
- Compression
- Tension
- Reaction force
What is gravitational (weight) force?
The force between any two objects with mass.
What is electrostatic force?
The force between any two objects with charge (like a proton and an electron).
What is thrust?
The force pushing a vehicle (like the push from rocket engines on the shuttle).
What is upthrust?
The upward force on any object in a fluid (like a boat on the surface of a river).
What is air resistance (drag)?
The force of friction between objects falling through the air (like a skydiver in freefall).
What is compression force?
Forces that squeeze an object (like squeezing a spring).
What is tension force?
Forces that stretch an object (like two teams in a tug-of-war).
What is the reaction force?
The force between any two objects in contact (like the upwards force from a table on a book).
What is a normal reaction?
That means its acting at 90* to the road surface.
How to calculate resultant forces?
Force acted on one side - force acting on the other side.
What is friction?
It is a force that opposes motion.
What is a vector quantity?
A quantity with magnitude and direction.
What is a scalar quantity?
A quantity that only has magnitude.
What is magnitude?
How much of a quantity.
What type is quantity is force?
Vector quantity.
What is the elastic behaviour of a material?
The ability of a material to recover its original shape after the forces causing deformation have been removed.
What does Hooke’s law state?
The extension of an object is directly proportional to the force causing it.
What are the steps taken to investigate how the extension of a spring changes with load?
- The length of the unstretched spring is measure with a half-meter ruler.
- The spring is then loaded with different weights.
- The extension is then recorded into a table of results.
- You then plot a graph of force (N) to extension (m).
How do you know if a spring obeys Hooke’s law?
When does Hooke’s law apply?
When you don’t stretch a spring too far.
What happens if a spring is stretched beyond its elastic limit?
It will not return back to its original length even if you take the weights off of the spring.
What does a force - extension graph look like if a spring has surpassed its elastic limit?
What other things can you use this test on?
- Wires
- Rubber bands.
Do wires obey Hookes law?
It depends on the metal used - some will obey the law until the wire breaks; other types will stretch elastically and then plastically before breaking.
Do elastic bands obey Hookes law?
The graph that is produced when replicating the experiment is not a straight line - showing that it doesn’t obey Hooke’s law.
What does a typical force-extension graph look like for elastic bands?
