Unit 2 Flashcards
What is a vector quantity?
Has magnitude and direction
Give an example of a scalor quantity
Distance, speed, time, power, etc.
Give an example of a vector quantity
Displacement, velocity, acceleration, force
What is displacement?
The direct distance from start to end
What is speed?
The distance traveled per unit time
What is velocity?
The displacement per unit time
To find a resultant force what would be used?
Pythagoras and trigonometry
Vectors can be combined to produce what?
A resultant vector
What is acceleration?
The change in velocity per unit time
What causes an object to accelerate when dropped?
An unbalanced force
Ignoring friction do all objects in free fall accelerate at the same rate?
Yes
On a velocity time graph, how is displacement calculated?
Area of each shape is found then added together
What is the unit of force and how can it be measured?
Newtons (N), using a Newton balance
When does a balanced force occur?
When an object has equal sized forces acting in opposite direction
What happens to the motion of an object when the forces are balanced?
Will be at rest or traveling in a straight line at a constant velocity
What happens to the motion of an object when the forces are unbalanced?
Object will be accelerating or decelerating
An object falling at terminal velocity will have what kind of forces acting on it?
Balanced forces. Weight down will balance with air resistance upwards
When does an unbalanced force occur?
When an object has forces acting on it that do not cancel each other out
When does friction occur?
When two surfaces are in contact while moving past each other
What is a scalor quantity?
Quality that only has magnitude
How can friction be reduced?
If the surface contact area is reduced or surface is smoother
When friction acts between surfaces what types of energy are there?
Kinetic energy is transformed into heat energy
What is Newton’s first law?
An object will remain at rest or remain at a constant velocity unless acted on by an unbalanced force
What is Newton’s second law?
The acceleration of an object is directly proportional to the unbalanced force and inversely proportional to the mass of an object
What is Newton’s third law?
If object A exerts a force on object B, then object A exerts an equal but opposite force on object A
What is mass?
The amount of matter in an object
What is weight?
The force on an object caused by the force of gravity
What is work done?
An amount of energy being transferred
When is a object a projectile?
If it has both vertical and horizontal motion
What happens to the vertical and horizontal motion in a projectile?
Horizontal velocity is constant. Vertical velocity is increasing
As the height (altitude) of a satellite increases, what happens to the period?
It increases
What are some uses of satellites?
Telecommunications, weather forecasting, satnav
How does a rocket take off in terms of forces and motion?
If the up thrust force remains constant, the unbalanced force increases and acceleration increases
When a space craft re enters Earth’s atmosphere, what does friction cause?
It transforms kinetic energy into heat energy
If the angle of re-entry is too steep what happens to the spacecraft?
Drag force is too large, too much heat and space craft is destroyed
If the angle of re-entry is too shallow what happens to the spacecraft?
Drag force is too small, spacecraft returns to orbit
What is used to protect spacecrafts during re entry?
Silica tiles?
Why are silica tiles used to protect spacecrafts?
They have a high melting point, good insulators, will remain a constant temperature as they melt. Painted black to radiate heat
What is specific latent heat?
The heat energy needed to change the state of 1kg of material
What is specific latent heat of vaporisation used for?
The change between liquid and gas
What is specific latent heat of fusion used for?
The change between a liquid and a solid
What type of energy is either absorbed or released when a material changes state?
Heat energy
What can be used to identify elements present within stars?
Spectra
Where does a continuos spectrum come from?
A hot white light source
Where does a line spectrum come from?
A hot gaseous element. Shows frequencies on a black background
What is a light year?
The distance light travels in one year
What is one light year?
9.47 x 10^15 m
What does a continuous spectrum contain?
All the wavelengths (colours) of light
