5. Forces (scalar and vector quantities & contact and non-contact forces) Flashcards
What is a scalar quantity?
A quantity that has magnitude only
What is a vector quantity?
A quantity which has both magnitude and direction
What are examples of scalar quantities?
- speed
- distance
- time
- mass
- energy
What are examples of vector quantities?
- velocity
- displacement
- acceleration
- force
- momentum
What can vectors be represented by?
arrows, with their size/length representing the vector magnitude
If a car is travelling around a roundabout at a constant speed, is it accelerating?
- While the speed is constant, it’s direction is constantly changing
- so it’s velocity is constantly changing, therefore it is accelerating
What is a force?
A push or pull that acts on an object due to the interaction with another object
What are the two types of forces?
Contact forces
Non-contact forces
What is a contact force?
When two objects are touching to exert a force
What is a non-contact force?
If two objects do not need to be touching to exert a force
What are the 4 contact forces?
- Friction
- Air-resistance
- Normal reaction force
- Tension
What are the 3 non-contact forces?
- electrostatic force
- magnetic
- gravitational
What is friction?
Two objects sliding past each other experience friction forces.
What causes friction?
The surfaces and their roughness, when moved in contact
How can friction be reduced?
Through lubrication or smoothing of two objects
What is Air-resistance?
- The force exerted by air particles when an object is in motion
- The larger the object, the more air-resistance is endured
What is air-resistance a type of?
friction
What is a normal reaction force?
- What keeps an object stationary
- Equal and opposite force
What is tension?
When an object is stretched, the force of tension is what tries to bring it back to its original shape
What is an electrostatic force?
- when two objects are electrically charged, and the charges cause a force of attraction/repulsion
What is a magnetic force?
Magnetic forces will be exerted from the poles of magnets
What is gravitational attraction?
The mass creates a force of attraction (is always attractive)
What does friction oppose?
motion
What is an interaction pair?
When two objects interact, the forces they exert on each other are equal and opposite
What things can forces change on an object?
- the shape of an object
- the speed of an object
- the direction of an object
