9) Forces & Their Effects Flashcards
What is a moment?
A moment is the turning effect of a force around a fixed point
How are moments calculated?
Moment = force x distance
What distance is used in moments calculations?
The perpendicular distance from the pivot
What is force measured in?
Newtons (N)
Whare are moments measured in?
Newton metres (Nm)
How is an object in equilibrium in linear motion?
There must be no resultant force acting on the object and it must be stationary or travelling at a constant speed in a straight line
How is an object in equilibrium in circular motion?
The sum of the clockwise and antioclockwise moments acting on the object must be equal, this means the object is not rotating or rotates at a constant speed
What can we use levers and gears to do?
Transmit the rotational effect from one place to another
What do levers do?
Increase the distance between the pivot and where we’re applying the force
How does the size of gears effect the moment?
Sending a force to a larger gear will create a larger moment as the distance to the pivot is greater
What is a force?
A push or pull that acts on an object when it interacts with another object
What are the two types of forces?
Contact
Non-contact
What are contact force examples?
Friction
Air resistance
Tension
Normal contact force
What are examples of non-contact forces?
Gravitational force
Electrostatic force
Magnetic force
How is air resistance a contact force?
When an object moves through the air it collides with air molecules, slowing it
How is friction created?
When two surfaces try to move against each other, tiny bumps in the surface interlock opposing the motion
What is an example of normal contact force?
When you push on your table it pushes equally on your hand
What does friction normally create?
Heat
What reduces friction?
Separating surfaces with a thin layer of oil
What are diagrams used to show forces acting on an object called?
Free body diagrams
What are forces shown as in free body diagrams?
Vectors
What can we use free body diagrams for?
Working out the resultant force of an object
Seeing if an object is in equilibrium
