Motion Flashcards
(29 cards)
Scalar Quantities and Vector Quantities
Scalar quantities have a magnitude (size), e.g: speed, distance and time.
Vector quantities have both magnitude and direction, e.g: velocity and displacement.
Displacement
The distance an object travels in a certain direction. It is also the shortest distance between a starting and finishing point (Different to distance).
Velocity
The speed of an object in the direction it is travelling in (Different to speed). E.g: 5m/s east
Velocity Formula
Velocity = Displacement ÷ Time Taken
Formula for Slope (On a Distance-Time Graph)
Slope (Same as Speed) = Change in Distance ÷ Change in Time
Acceleration
When speed changes over time.
Formula for Acceleration and Unit of Acceleration
Acceleration = Change in Speed (m/s) ÷ Time Taken (s)
Unit of Acceleration = m/s/s, or m/s(squared)
Acceleration also = Change in Velocity ÷ Time Taken
Force
Explains why an object moves the way it does, why things stretch, twist, tear, snap, bend, break, speed up, slow down, change shape and change direction.
5 Examples of Contact Forces
- Pushes and pulls, e.g: rugby tackle
- Friction, e.g: slows down cars on roads
- Support Forces, e.g: keeps you upright when you stand on the ground
- Tension, e.g: pulls a bungee jumper back
- Surface Tension, e.g: keeps insects floating on water
3 Expamples of Non-Contact Forces
- Gravity, e.g: pulls objects towards the Earth
- Magnetict forces, e.g: pulls on metals (such as iron, nickel and cobalt)
- Electrostatic forces, e.g: when the hairs on your arm are attracted to a T.V screen
Measuring Forces and the SI Unit for Force
Forces are measured using a newton meter (spring balance).
Can also be measured digitally using a force meter.
The SI unit for force is the newton (N).
Equilibrium
A state of balance between opposing forces.
Unbalanced forces cause objects to slow down, speed up or change direction.
Dynamic Equilibrium
Forces are equal but the object continues to move with a constant speed.
Friction
A force that opposes motion when two objects are placed in contact.
Examples of Drag Forces
Water Resistance and Air Resistance
Lubrication
Used to reduce friction between two solids, e.g: oiling a bicycle
Streamlining
Reducing drag forces in wind and air, e.g: dolphins so they can move through water easily.
Reaction force
Example: The force applied by the table in response to the weight of a person. Example of an interaction pair.
Elastic Object
An object that is able to restore its shape after it has been stretched or compressed.
Elastic Limit
The point that an elastic object is extended to so that it will not restore its shape.
Pressure
The amount of force over a unit of area.
Equation for Pressure and Unit of Pressure
Pressure = Force Applied (N) ÷ Area It Is Applied Over (m squared)
Unit of Pressure = N/m squared
Pressure in Liquids
In liquids pressure increases with depth. The bottom of something in a liquid will always feel the most pressure. Liquids at a given depth, exert pressures equally in all directions. They do this because they can flow.
Pressure in Gases
As gas particles move around, they collide with other objects and with each other. They exert a force. This force applied over an area causes gas pressure. The faster the gas particles move, the greater the pressure is. Example: compressing gas particles into balloon, the number of collisions increases, increasing pressure, causing it to inflate.
