3.2.2.5 Projectile motion

Question 1

projectiles

Answer 1

objects in flight

e.g. humans, shot-put, javelin

Question 2

projectiles governed by…

which forces?

Answer 2

following forces:

1. gravity (downwards)
2. air resistance (opposite direction to objects motion)

& direction of motion (linked to angle/speed/height of release)

Question 3

speed of release

Answer 3

affects flight greater release velocity/speed = horizontal displacement increase
e.g rotation of shot-putter designed to ensure shot leaves performers hand at max velocity

Question 4

height of release

Answer 4

increase height of release = increase horizontal displacement
gravity acting so try to release at highest point
e.g. taller shot putters = adv over shorter ones

Question 5

angle of release

Answer 5

optimum angle of release = dependent upon relative heights of release and landing

Question 6

forces determining projectile flight

Answer 6

once released 2 forces determine projectile flight

1. gravity
2. air resistance

Question 7

gravity

Answer 7

act on body in flight
whether gravity predominant force - affect shape of flight path
gravity only force = shape flight path = parabola
y-axis height reached
x-axis horizontal displacement(distance travelled)

Question 8

force vectors

Answer 8

gravity acting down throughout

Question 9

stages velocity vectors

Answer 9

1. peak = no vertical velocity
2. horizontal forces same throughout no force acting in horizontal (no air resistance)
3. accelerates downwards

Question 10

vector components for parabolic flight

Answer 10

air resistance = negligible = horizontal velocity vector component stays the same throughout flight

gravity = only vertical force acting on body, vertical vector component changes at rate of 9.8m/s

Question 11

air resistance

Answer 11

opposite direction to motion 
faster projectile = greater air resistance 
relative size of force is key 
larger if relative mass of object less 
flight path = asymmetric

Question 12

velocity vs air resistance

Answer 12

travels slow = air resistance small
air resistance decreases as the speed decreases
fast moving shuttlecock = greater air resistance

Question 13

how flight is affected by forces?

3 forces & how they affect flight?

Answer 13

gravity & air resistance
gravity = constantly/continuously accelerating projectile downwards throughout flight
air resistance = slows down once in flight

muscular forces = point of release (only force acting) exerted on, net force = dependent on horizontal and vertical

Question 14

muscle groups produce same max vertical and horizontal motion? high jump e.g.

Answer 14

vector = magnitude & direction = split into horizontal&vertical components

high jump = greater vertical component by pushing down into the ground = cause larger upwards acceleration due to GRF = higher jump, muscles exert a force down onto the ground & ground exerts equal &opposite force on high jumper = movement upwards

Question 15

sprinter e.g.
forces acting ?
components?

Answer 15

sprinter = greater horizontal component
muscles exert force on the ground and equal and opposite force is friction = pushes sprinter forwards and acceleration

sprinter push backwards with their muscles (less downwards) = cause larger frictional force forwards = larger horizontal acceleration = maximise forward velocity and a faster race

Question 16

parabolic flight

Answer 16

large weight & negligible air resistance force
1 force = gravity = decreases vertical component act downwards from +ve to -ve
symmetrical (parabola)
balls motion has vertical &horizontal components

Question 17

factors affecting horizontal displacement?

Answer 17

1. speed of release
2. angle of release
3. height of release

Question 18

horizontal displacement

Answer 18

shortest distance from starting point to finishing point in a line parallel to the ground

Question 19

release and landing height equal

Answer 19

optimum 45 e.g long jump

Question 20

release > landing height

Answer 20

optimum angle <45 e.g. shot-put

Question 21

release < landing height

Answer 21

optimum > 45 e.g basketball shot/chip in golf

Question 22

non parabolic flight

Answer 22

lighter mass,
account for effects of air resistance
e.g. badminton shuttle cock

Question 23

parabola

Answer 23

curve with matching left and right hand sides