Projectile Motion Flashcards
state what it is meant by the key term - ‘projectile motion’
projectile motion is the motion observed when bodies are projected into the air and are under the influence of gravity (and air resistance) only
what is the value of acceleration due to gravity on earth ?
- 9.81 m/s^2
state what it is meant by the key term - ‘projectile’
a projectile is a body that is undergoing projectile motion
what can a projectile be in S+E ?
in S+E, a projectile can be an object (eg - equipment), a body, or both (a system)
state what it is meant by the key term - ‘gravity’
gravity is the attraction influence (force) that pulls objects towards the earth’s surface
state what it is meant by the key term - ‘air resistance’
air resistance is a frictional force that occurs when air pushes over the surface of a body
state an expansionary fact about ‘gravity’
gravity uniformly accelerates a projectile towards the earth’s surface at - 9.81 m/s^2
state 2 expansionary facts about ‘air resistance’
- limits the motion of a projectile
2. compared to gravity, air resistance is often minimal/negligible, so is often neglected
state what it is meant by the key term - ‘trajectory’
trajectory - the flight path of an object through the air
state what it is meant by the key term - ‘parabola’
parabola - the trajectory follows a ‘parabolic’ curve shape that is symmetrical about its apex
state what it is meant by the key term - ‘apex’
apex - the highest point reached by a projectile
state what it is meant by the key term - ‘range’
range - the horizontal displacement of a projectile
state the 3 determinants of projectile motion
- projection angle
- projection velocity
- projection height
state the 2 influences imposed by the projection angle
- the angle at release determines the shape of the trajectory, all other factors being equal
- projectile angle influences the relative magnitude of the vertical and horizontal components
a positive angle is > 0’, state 2 facts
- between 0-90 degrees = oblique trajectory
2. parabolic shape, symmetrical about the apex
0 degrees = horizontal trajectory (horizontal with the ground). state 2 facts
- if no projection height, there will be no flight
2. if projection height, trajectory resembles one half of a parabola
90 degrees, vertical trajectory. state 1 fact
projectile follows the flight path up and down with no range
a negative angle is < 90 degrees, below horizontal. state 1 fact
not considered for projectile motion
state what it is meant by the key term - ‘projectile velocity’
projectile velocity determines the height and range of a projectile, all other things being equal
what determines the height and time of flight ?
vertical velocity (Vy) determines the height and time of flight
what is the formula for Vy ?
Vy = V x sin(θ)
what is the formula for ‘time of flight’ ?
Δt = 2 x ((Vy,f - Vy,i) / a)
state the 2 formulae to work out maximum height
displacement (s) = (Vy,i x Δt) + 1/2 x a x Δt
displacement (s) = (Vy,f^2 - Vy,i^2) / (2 x a)
what does horizontal velocity determine ?
horizontal velocity determines the range
what is the formula for horizontal distance ?
Vx = V x cos(θ)
state what it is meant by the key term - ‘projection height’
projection height is the relative distance between the point of release and the point of landing
state 5 key features about projection height = 0
- symmetrical about apex
- parabolic
- time up = time down
- displacement up = displacement down
- max range produced at 45 degree angle
state 6 key features about projection height > 0
- non-symmetrical about apex
- parabolic
- time up < time down
- displacement up < displacement down
- can be manipulated by technique to provide a mechanical advantage
- optimal projection angle = < 45 degrees
state 6 key features about projection height < 0
- non-symmetrical about apex
- parabolic
- time up > time down
- displacement up > displacement down
- generally a disadvantage for projectile motion imposed by the nature of the task
- max range produced with a projection angle > 45 degrees
state the 3 goals for projectiles in sport
- predicting a trajectory (eg - receiving a pass)
- controlling a trajectory (eg - shooting)
- maximising/optimising aspects of a trajectory (eg - throwing events)
state 3 facts to explain the problems we encounter with the shot put when talking about projectile motion
- theory suggests that a projection height > 0 has an optimal release height of < 45 degrees
- for a typical elite throw, release height of 2.15 m, optimal angle should be 42 degrees
- but, elite throwers release at 37 degrees
what does it mean when it says release angle, height and velocity are not independent ?
changing one will effect the others
what is the first SUVAT equation ?
v = u + at
what is the second SUVAT equation ?
s = ut + 1/2 at²
what is the third SUVAT equation ?
v² = u² + 2as
what is the fourth SUVAT equation ?
s = (v + u / 2) x t
what is the fifth SUVAT equation ?
s = vt - 1/2 at²
