Acceleration and Equations of Motion Flashcards
acceleration
change of velocity per unit time
acceleration equation
(v-u)/t
What is a method of measuring acceleration?
single card 2 light gates computer measure velocity of each light gate and time between
measuring distance travelled on graph
total area under speed-time graph
measuring displacement on graph
total area under velocity-time graph
Describe this velocity-time graph.
accelerates for 10min constant velocity of 60m/min for 5min decelerates for 15 mins accelerates for 10 mins in opposite direction decelerates for 15 mins
derive v = u + at
- a = (v-u)/t
- v = u + at
derive s = ut + ½at²
- s = vt
- replace v with average velocity s = ((u+v)/2)t
- subsititue in v = u + at
- s = ½(u + (u + at))t
- s = ½(2u + at)²
- s = ½(2ut + at²)
- s = ut + ½at²
derive v² = u² + 2as
- v = u + at
- t = (v – u)/a
- s = ½(u + v)((v – u)/a)
- s = ((v + u)(v – u))/2a
- 2as = (v + u)(v – u)
- 2as = v² – u² v² = u² + 2as
derive s = ½(u + v)t
- average velocity = (u + v)/2
- s = ((u + v)/2)t
- s = ½(u + v)t
deceleration
acceleration decreases (negative acceleration)
any object freely moving through the air is… towards the ground under the influence of…
accelerated gravity
what does gravity provide?
doward acceleration of 9.81m/s^2
what happens the instant an object is dropped?
stationary so u = 0m/s
what is the accleration of a dropped object?
-9.8m/s^2
what is the initial velocity of an object launched upwards?
u = maximum upward velocity
what happens when an object reaches its maximum height?
v = 0m/s
projectile
any object that is thrown, launched or falls through air
trajectory
path travelled by projectile
what effect does air resistance have on values obtained in experiments involving projectiles?
slightly lesser
horizontal projectiles horizontal velocity
remains constant until hits the ground
horizontal projectiles the larger the horizontal component, the … the range
larger
horizontal projectiles horizontal acceleration
no acceleration
horizontal projectiles horizontal displacement equation
horizontal velocity x time
horizonal projectiles vertical initial velocity
u = 0m/s
horizontal projectiles vertical acceleration
gravity
horizontal projectiles the greater the initial vertical velocity the … the final velocity just before hitting the ground
greater
what shape does a projectile fired from ground have?
symmetrical parabolic trajectory
range
horizontal distance travelled
when does the projectile reach its maximum height?
half its range half time taken to complete journey
how to split projectile motion into horizontal and vertical components?
vertical = usinO horizontal = ucosO
what remains constant during projectile motion?
horizontal component
how to graph the vertical component of velocity?
How does horizontal motion show that air resistance is negligible?
displacement constant
therefore velocity constant
no acting horizontal force
How to explain vertical motion of projected object?
object accelerates due to gravity
constant acceleration
If air resistance is not negligible what effect does this have on…
- horizontal motion?
- vertical motion?
- horizontal displacement less
- accelerates less vertically
- effect of air resistance increases with time
- reaches terminal velocity
Why is horizontal motion constant?
no horizontal force therefore no horizontal acceleration
Why does acceleration decrease down a ramp?
component of weight down slope causes acceleration
component decreases as moves down slope
air resistance and friction increase with speed
