Y2 - C8 - Further Kinematics Flashcards
What is kinematics
The study of motion that ignores forces
What is the position vector (r) of a particle equal to
r = r0 + vt
(displacement = velocity x time)
Where ro is the initial position
v is velocity
t is time
A particle starts from (3i + 7j) and moves with constant velocity (2i - j), find the time at which the particle is due east of the origin
j component = 0 when east of origin
(3 + 7j) + t * (2i - j) = (xi, 0j)
7 + t * -1 = 0
t = 7
What does it mean if letters are underlined
They are vectors
What does distance (s) become in suvat equations when using vectors
r (displacement)
Which suvat equations can’t you use with vectors
v^2 = u^2 + 2as
What do:
s = ut + 0.5at^2
s = vt - 0.5at^2
become when using vectors from an initial position
r = r0 + ut + 0.5at^2
r = r0 + vt - 0.5at^2
where ro is the initial position
When a vector question asks you for the speed what must you do
Find the magnitude of the velocity vector
Where do you take the angle for a bearing from
The north (y axis)
How do you write bearings
3 digits and a degrees sign
e.g. 018^o
How do you find the time when a particle is directly a) north-east, b) north-west of the origin
a) Set the i and j components equal (e.g. both to x) and solve simultaneously
b) Set i to x and j to -x
How do you show that two particles meet at the same point at the same time
Set their position vector equations and solve for t
Sub the t value back into both equations to prove that their position vectors match at that time
What does r0 mean
The initial displacement
What can you do with suvat equations for projectiles when they are in vector form
Combine them into one equation rather than resolving into horizontal and vertical components
When combing vectors to solve projectile motion questions, what direction should you take vertically and horizontally
Upwards vertically
Right or left horizontally depending on the direction the particle moves
