S1 Physics Notes Flashcards
Define a “scalar” quantity (brackets highlight key points)
A quantity that can be (accurately described) using only its (magnitude) and (units)
Define a “vector” quantity
A quantity that can only be (accurately described) using its (magnitude), (units) and (direction)
What is the difference between distance and displacement?
(Distance) is a (scalar quantity) and (displacement) is the (vector equivalent)
What is the difference between speed and velocity?
(Speed) is a (scalar quantity) and (velocity) is the (vector equivalent)
= speed requires magnitude where velocity requires direction and magnitude
Define velocity and give the units it’s measured in
(Speed) in a (given direction), (metres per second) / (m/s)
Define displacement and give the unit it’s measured in
(Distance) travelled in a (given direction), (metres) / (m)
Apart from direction, what is the other difference between scalar and vector quantities?
(Scalars) (cannot) have (negative units), whereas (vectors) (can) have (negative units)
What is a negative unit used to express?
(Backwards movement) (relative) to the (starting point)
Define constant speed/velocity
(Moving) at a (steady/constant rate)
Define uniform acceleration
When speed/velocity is increasing or decreasing a constant rate
Define acceleration and the give the units it’s measured in
(Change) in (velocity) over (unit time), (metres per second squared) / (m/s2)
What is a ticker tape timer and how does it work?
A (ticker tape timer) is a device that (stamps a strip of ticker tape) with a dot (many times a second). This can be used to analyse motion by looking at the (frequency of the dots). The (farther apart) the dots are the (faster) the object is (moving). We can use this data to (calculate speed) by taking the (distance between 2 dots) and (dividing) it by the (frequency of the dots), i.e. (5 dots per second/1 dot per 0.2 seconds). For example: (1cm/0.2s = [5cm/s])
What does the gradient of a displacement/time graph represent?
(Speed/velocity)
What does the gradient of a velocity/time graph represent?
(Acceleration)
What does a curve on d/t graph represent?
Acceleration (represented by upward curve) / deceleration (downward curve)
What does a curve on a v/t graph represent?
(Non-constant) acceleration/decelerartion
What does the area under the gradient of a v/t graph represent?
(Displacement)
What do the variables s, u, v, a and t represent in an equation?
s = displacement
u = initial velocity
v = final velocity
a = acceleration
t = time
What is the equation for average velocity?
v = u +at
OR
v = d/t
Equations for distance
s = (u+v)t / 2
s = ut + 1/2 at2
s = v/t
Equation for final velocity
v2= u2 + 2as
Or
v= u + at
Or the rearranged equation from
S= ut + 1/2at2
What is Newton’s First Law of motion?
A body will remain at rest or travel at a constant speed unless compelled to change by an external force
What is inertia?
(Reluctance) to (start moving) when at (rest) or (reluctance) to (stop moving) when in (motion)
What 2 physical states can an object be in when the forces acting on it are balanced?
(Stationary) / (moving at constant speed)
What is Newton’s Second Law?
The resultant force produced is directly proportional to the acceleration and inversely proportional to the mass
F = ma
How else can Newton’s second law be written (equation)?
F = ma
What is Newton’s Third Law?
If (body A) exerts a (force) on (body B) then (body B) will exert a (force) on (body A) that is (equal in magnitude) but (opposite in direction)
What effects can forces have on objects (3)
They cause a change in the
1. motion,
2. size, or
3. shape of a body
What is the difference between mass and weight?
(Mass) is (unchanging) and is measured in (kilograms/kg), whereas (weight) is the (effect of gravity) on an object’s (mass) and is measured in (Newtons/N)
What is Hooke’s Law? (Give definition, formula and units)
The extension of a spring is proportional to the stretching force so long as the spring is not permanently stretched
F = kx
F
K x
= N=N/m x m
(Spring force = spring constant x extension)
What apparatus is used to measure weight?
(Newton Spring Balance)
Define “pressure”
The (force) acting on (unit area)
Give the formula and the SI unit for pressure
P = F/A
N/m2 / Pa
1N/m2 = 1Pa
Pa