Forces Flashcards
What is a force?
A force is a push or a pull on an object when it interacts with another object
What is an interaction pair?
When two objects interact with each other, a pair of forces exist
How do you measure forces?
The units for force are Newtons (N) and force can be measured using a Newton meter
Parallax error - reading equipment at an angle. Fix by reading at eye level
Zero error- when equipment doesn’t start at zero. Fix by using the dial at the top of the newton meter which resets it.
What are the 3 forces acting on moving objects?
Friction - slows moving objects along a solid surface
Air resistance- slows moving objects that travel through air
Water resistance- slows moving objects that travel through water
Describe friction
Friction makes it more difficult for things to move because surfaces rub against each other.
Can be useful e.g friction in our shoes stops us from slipping
Can be unhelpful e.g if shoes touch feet you may get blisters
Friction is smaller on smooth surfaces
Friction can be increased by making surfaces rougher. Can be reduced by making surfaces smoother e.g through lubrication
Describe drag forces
Air + water resistance = drag
Streamlined objects move faster through air/water because they reduce the force acting on them
Describe balanced forces
If the forces acting on an object are equal and in opposite direction, then they are balanced/equilibrium
Force can be represented using a free body diagram
Tail of arrow - where force is acting
Head of arrow - direction of force
Length of arrow - size of force
What is gravity?
A force of attraction between any objects with mass
What is the difference between Mass and Weight?
Mass:
- How much
matter (stuff) an object is made of
- Measured in g
- Does not depend on the gravitational field of planet
Weight
- The force of gravity on an object
- Measured in Newtons (N)
- Depends on the gravitational fueld5
What is Hooke’s law?
For a spring, the force applied is directly proportional to the extension of the spring
If we double the force applied, the extension also doubles
How do you calculate weight?
Weight (N) = mass (KG) × gravitational field strength (N/KG)
W = M × G
Mass as in mass of the object
Gravitational field strength which is determined by the objects around it and the planet itself.
Describe resultant forces
If the resultant force is 0 N, the speed is constant
Why does drag occur?
A solid moving through a liquid or gas has to push the particles away. This produces a drag force on the object
