Projectile Motion Flashcards
examples of projectile motion
- long jump
- high jump
- shot put
- ball toss
- running (flight phase)
- free throw
force that acts before the object is a projectile
results in initial velocity
after release, what external force acts on projectile?
only gravity (constant accel. = -9.81 m/s^2)
uniform motion
velocity is constant, so acceleration = 0
uniformly accelerated motion
object is undergoing constant acceleration (due to gravity)
constant velocity
constant acceleration, accel-time curve is constant (slope = 0) and equal to -9.81 m/s^2
T/F: horizontal and vertical components of velocity are independent and should be treated separately
True
when is velocity at its peak in vertical motion of a projectile?
closer to the ground, right before it hits ground
what is the initial and final velocity of a person who jumps up/out and lands on the ground?
initial v = positive
up: magnitude of v decreases
v at peak = 0
down: magnitude of v increases
final velocity = negative
what shape is the path of a projectile?
parabola (when air resistance ignored)
does the COM of a body or object follow the parabolic path even if there are complex motions of other segments?
yes
time in air - for the same vertical take-off and landing positions
t up = t down
horizontal displacement - for the same vertical take-off and landing positions
d H-up = d H-down
displacement up vs. down - for the same vertical take-off and landing positions
d y-up = d y-down
vertical velocity (up)
positive
vertical velocity at peak height
v = 0
vertical velocity (down)
negative
is horizontal velocity of a projectile constant?
yes, it does not change during flight phase b/c there is no acceleration
if a soccer ball has a horizontal velocity of 20 m/s what is the acceleration?
horizontal accel = 0
what is the horizontal velocity of the soccer ball at t = 1,2,3,4,5 s?
no accel so v = 20 m/s at every instant
what is the horizontal distance at t = 1,2,3,4,5 s?
v = 20 m/s so 20 m, 40 m, 60 m, 80 m, 100 m
three factors that influence the trajectory of a projectile
- projection angle
- projection velocity
- relative height of projection (h)
what projection angle produces the largest horizontal displacement?
45 degree angle
projection angle - maximal height
90 degrees
projection angle - maximal distance
45 degrees
what is the most important factor that influences horizontal displacement?
projection velocity
if you increase velocity, what happens to displacement?
displacement increases
projection height =
release height - landing height
release ht = landing ht
projection height = 0
release ht > landing ht
positive value
release ht < landing height
negative value
two factors that determine flight time
- vertical speed at release
- height of release
take off position = landing position
t up = t down
take off position > landing position
t up < t down
take off position < landing position
t up > t down
what happens when release height is greater?
- distance down increases
- time down increases
- horizontal distance increases (due to more time in air)
what happens when landing height is greater?
- distance down decreases
- time down decreases
- horizontal distance decreases (due to less time in air)
factors influencing flight time
- initial vertical velocity
- relative projection height
factors influencing horizontal displacment
- initial vertical velocity
- relative projection height
factors influencing trajectory
- initial resultant velocity
- projection angle
- relative projection height
