Forces and Motion Flashcards
Define force and state its units
A push or pull, it has both size and direction. (Newtons (N))
Force can make an object do what?
Force can make things move, change shape or change their speed.
Distinguish between a balanced and un balanced force and be able to recognise them on a force diagram.
Balanced forces are forces of equal magnitude but are opposite in direction. Objects acted upon by balanced forces remain at rest or stay in motion at a constant speed. Unbalanced forces, on the other hand, are not equal in magnitude and may or may not be directed in the same direction.
Understand that weight is a force and state its units.
Distinguish between mass and weight.
Weights’ units: (g/kg)
Mass is a fundamental measurement of how much matter an object contains. Weight is a measurement of the gravitational force on an object.
Define friction and give common examples
Friction is a force that tends to stop two things from sliding over each other. Example: Car Breaks, Shoes
What is a lubricant and give example about how it is used in relation to friction?
Lubricants such as grease and oil can be used to reduce friction and prevent wear and tear.
Positives and negatives in relation to friction.
Positives:
* Car tyres can push against the surface of the road, so the car can move forward.
* Brake blocks can squeeze against a bicycle wheel rim, so that the bike slows down.
* Shoes can grip the floor, so that you do not slip when you try to walk.
Negatives:
* It slows moving things down, and extra force is needed to keep them moving
* It can heat things up and can damage the moving surfaces.
Define air resistance and give an example. Understand that terminal velocity refers only to free falling objects.
Air resistance is a type of friction between air and another material. For example, when an aeroplane flies through the air, air particles hit the aeroplane making it more difficult for it to move through the air.
What is the law of the lever and be able to label a
fulcrum, a load and so forth.
The longer the lever, and the further the effort acts from the pivot, the greater the force on the load will be.
State the moments equation and the correct units.
Moment (Ncm/m) = Force (N) multiplied by the Perpendicular Distance to the Pivot (cm/m)
State the law of moments and balance moments using
the moments equation.
The Principle of Moments states that when a body is balanced, the total clockwise moment about a point equals the total anticlockwise moment about the same point. Moment =force F x perpendicular distance from the pivot d.
State the pressure equation and the correct units
Pressure (N/cm^2 or m^2) = Force (N) / A (cm^2 or m^2)
State Hooke’s law and be able to describe an experiment to demonstrate the law
Hooke’s law: The extension of a spring is directly proportional to the force applied, provided that the limit of proportionality is not exceeded.
The Hooke’s Law experiment is conducted by suspending an object from a spring scale and measuring the amount of force required to maintain the object in a stationary position.
