play phryzby with physics

As High as It Goes Far

solved Projectile

Q. A cricketer can throw a ball at mostθ(f₀)=45° 100 mxx(f₁)=100m. How highθ(h₀)=90°, vy(h₁)=0m/s can they throw the same ballv(h₀)=v(f₀), in metres?

v₀θ = 45°vy = ?t fart highg = 9.8 m/s²
Inputs
xx
100.00 m
Outputs
heightxy?

How it's solved

Solved with Projectile

Given

  • xx(f₁)=100m
  • θ(f₀)=45° from “at most”
  • θ(h₀)=90° from “How high”
  • vy(h₁)=0m/s from “How high”
  • v(h₀)=v(f₀) from “the same ball”

Assumed

  • g=9.8m/s²
  • xx(f₀)=0m
  • xy(f₀)=0m
  • xy(f₁)=0m
  • xy(h₀)=0m

Find xy(h₁).

Working
  1. falling freely(far, y)ay(f)=−g
  2. ay(f)=−9.8
  3. ay(f)=−9.8m/s²
  4. falling freely(far, x)ax(f)=0
  5. ax(f)=0m/s²
  6. parts of a velocity(ball, start of far, y)vy(f₀)=v(f₀)⋅sin⁡θ(f₀)
  7. position after a time(far, y)xy(f₁)=xy(f₀)+vy(f₀)⋅Δtf+ay(f)⋅Δtf22
  8. position after a time(far, x)xx(f₁)=xx(f₀)+vx(f₀)⋅Δtf+ax(f)⋅Δtf22
  9. parts of a velocity(ball, start of far, x)vx(f₀)=v(f₀)⋅cos⁡θ(f₀)
  10. v(f₀)=31.3049517m/s
  11. the same ballv(h₀)=v(f₀)
  12. v(h₀)=31.3049517
  13. v(h₀)=31.3049517m/s
  14. parts of a velocity(ball, start of high, y)vy(h₀)=v(h₀)⋅sin⁡θ(h₀)
  15. vy(h₀)=31.3049517⋅sin⁡90°
  16. vy(h₀)=31.3049517m/s
  17. falling freely(high, y)ay(h)=−g
  18. ay(h)=−9.8
  19. ay(h)=−9.8m/s²
  20. velocity after a time(high, y)vy(h₁)=vy(h₀)+ay(h)⋅Δth
  21. 0=31.3049517+(−9.8)⋅Δth
  22. Δth=3.19438282s
  23. position after a time(high, y)xy(h₁)=xy(h₀)+vy(h₀)⋅Δth+ay(h)⋅Δth22
  24. xy(h₁)=0+31.3049517⋅3.19438282+(−9.8)⋅3.1943828222
  25. xy(h₁)=50.00 m
Conclusion

The farthest throw, at forty-five degrees, and the highest, straight up, both depend on the square of the speed over the pull, and the height is always half the range.

The web of concepts

given read from the words equation asked

The Ruby that solves it

The question and its solution are small Ruby files. The engine runs them.

question.rb
1require_relative "../physics"23question :as_high_as_it_goes_far do4  kind :numerical5  describes "A cricketer can throw a ball at most %{farthest}. %{height}, in " \6          "metres?"7  given farthest: "100 m"8  asks height: "How high can they throw the same ball"9end
solution.rb
1require_relative "../questions/as_high_as_it_goes_far"2require_relative "../science/motion_in_a_plane/projectile"34solve :as_high_as_it_goes_far, using: Projectile do5  objects :ball6  axes :x, :y7  ball.goes(:far)8  ball.goes(:high)9  take farthest: ball.position(at: far.end, along: x)10  assume g: "9.8 m/s2"11  assume ball.position(at: far.start, along: x) => "0 m", ball.position(at: far.start, along: y) => "0 m",12         ball.position(at: far.end, along: y) => "0 m", ball.position(at: high.start, along: y) => "0 m"13  deduce_from "at most", ball.direction(at: far.start) => "45 deg"14  deduce_from "How high", ball.direction(at: high.start) => "90 deg"15  deduce_from "How high", ball.velocity(at: high.end, along: y) => "0 m/s"16  deduce_from "the same ball", ball.speed(at: high.start) => ball.speed(at: far.start)17  height = ball.position(at: high.end, along: y)18  answer height:, in: "m"19  conclusion "The farthest throw, at forty-five degrees, and the highest, straight up, both " \20             "depend on the square of the speed over the pull, and the height is always half the " \21             "range."22end
playground.rb
1require_relative "../solutions/as_high_as_it_goes_far"23play_with :as_high_as_it_goes_far do4  title "As High as It Goes Far"5end
The laws it drew on
quantitywrittenunitswithinfrom
volumevolume——Vectors
massmass——Vectors
speedspeed——Vectors
densitydensity——Vectors
number of molesn——Vectors
angular frequencyangularfrequency——Vectors
workwork——Vectors
currentcurrent——Vectors
temperaturetemperature——Vectors
pressurepressure——Vectors
timets0 … 1e+05Vectors
powerpower——Vectors
total path lengths——Vectors
energyenergy——Vectors
gravitational potentialgravitationalpotential——Vectors
coefficient of frictionμ——Vectors
chargecharge——Vectors
accelerationam/s²—Vectors
velocityvm/s—Vectors
displacementΔxm—Vectors
angular velocityangularvelocity——Vectors
forceforce——Vectors
angular momentumangularmomentum——Vectors
linear momentumplin——Vectors
electric fieldelectricfield——Vectors
average velocityvavm/s—Vectors
magnetic momentmagneticmoment——Vectors
relative velocityvAB——Vectors
impulseimpulse——Vectors
first vectorA—0 … ∞Vectors
second vectorB—0 … ∞Vectors
angle betweenφ—0 … 3.142Vectors
resultantR—0 … ∞Vectors
resultant directionβ—0 … 3.142Vectors
directionα—-3.142 … 3.142Vectors
x componentAx——Vectors
y componentAy——Vectors
positionxm—Velocity
path lengthdm—Velocity
time takenΔts0 … 1e+05Velocity
average speedcavm/s—Velocity
starting positionx0m—Velocity
final positionxm—Velocity
change of velocityΔvm/s—Acceleration
average accelerationaavm/s²—Acceleration
starting velocityv0m/s—Acceleration
final velocityvm/s—Acceleration
gravitygm/s²—UniformAcceleration
displacement of ball during far along xΔxx(f)m—
position of ball at end of far along xxx(f₁)m—
position of ball at start of far along xxx(f₀)m—
displacement of ball during far along yΔxy(f)m—
position of ball at end of far along yxy(f₁)m—
position of ball at start of far along yxy(f₀)m—
displacement of ball during high along xΔxx(h)m—
position of ball at end of high along xxx(h₁)m—
position of ball at start of high along xxx(h₀)m—
displacement of ball during high along yΔxy(h)m—
position of ball at end of high along yxy(h₁)m—
position of ball at start of high along yxy(h₀)m—
average velocity of ball during far along xvav,x(f)m/s—
time taken of farΔtfs0 … 1e+05
average velocity of ball during far along yvav,y(f)m/s—
average velocity of ball during high along xvav,x(h)m/s—
time taken of highΔths0 … 1e+05
average velocity of ball during high along yvav,y(h)m/s—
average speed of ball during farcav(f)m/s—
path length of ball during fard(f)m—
average speed of ball during highcav(h)m/s—
path length of ball during highd(h)m—
change of velocity of ball during far along xΔvx(f)m/s—
velocity of ball at end of far from ground along xvx(f₁)m/s—
velocity of ball at start of far from ground along xvx(f₀)m/s—
change of velocity of ball during far along yΔvy(f)m/s—
velocity of ball at end of far from ground along yvy(f₁)m/s—
velocity of ball at start of far from ground along yvy(f₀)m/s—
change of velocity of ball during high along xΔvx(h)m/s—
velocity of ball at end of high from ground along xvx(h₁)m/s—
velocity of ball at start of high from ground along xvx(h₀)m/s—
change of velocity of ball during high along yΔvy(h)m/s—
velocity of ball at end of high from ground along yvy(h₁)m/s—
velocity of ball at start of high from ground along yvy(h₀)m/s—
average acceleration of ball during far along xaav,x(f)m/s²—
average acceleration of ball during far along yaav,y(f)m/s²—
average acceleration of ball during high along xaav,x(h)m/s²—
average acceleration of ball during high along yaav,y(h)m/s²—
acceleration of ball during far along xax(f)m/s²—
acceleration of ball during far along yay(f)m/s²—
acceleration of ball during high along xax(h)m/s²—
acceleration of ball during high along yay(h)m/s²—
velocity of ground at start of far from ground along xvg,x(f₀)m/s—
velocity of ground at start of far from groundvg(f₀)m/s—
direction of ground at start of far from groundθg(f₀)—-3.142 … 3.142
velocity of ground at start of far from ground along yvg,y(f₀)m/s—
velocity of ground at end of far from ground along xvg,x(f₁)m/s—
velocity of ground at end of far from groundvg(f₁)m/s—
direction of ground at end of far from groundθg(f₁)—-3.142 … 3.142
velocity of ground at end of far from ground along yvg,y(f₁)m/s—
velocity of ground at start of high from ground along xvg,x(h₀)m/s—
velocity of ground at start of high from groundvg(h₀)m/s—
direction of ground at start of high from groundθg(h₀)—-3.142 … 3.142
velocity of ground at start of high from ground along yvg,y(h₀)m/s—
velocity of ground at end of high from ground along xvg,x(h₁)m/s—
velocity of ground at end of high from groundvg(h₁)m/s—
direction of ground at end of high from groundθg(h₁)—-3.142 … 3.142
velocity of ground at end of high from ground along yvg,y(h₁)m/s—
velocity of ball at start of far from groundv(f₀)m/s—
direction of ball at start of far from groundθ(f₀)—-3.142 … 3.142
velocity of ball at end of far from groundv(f₁)m/s—
direction of ball at end of far from groundθ(f₁)—-3.142 … 3.142
velocity of ball at start of high from groundv(h₀)m/s—
direction of ball at start of high from groundθ(h₀)—-3.142 … 3.142
velocity of ball at end of high from groundv(h₁)m/s—
direction of ball at end of high from groundθ(h₁)—-3.142 … 3.142
displacement of ball during farΔx(f)m—
position of ball at end of farx(f₁)m—
position of ball at start of farx(f₀)m—
displacement of ball during highΔx(h)m—
position of ball at end of highx(h₁)m—
position of ball at start of highx(h₀)m—
average velocity of ball during farvav(f)m/s—
average velocity of ball during highvav(h)m/s—
change of velocity of ball during farΔv(f)m/s—
change of velocity of ball during highΔv(h)m/s—
average acceleration of ball during faraav(f)m/s²—
average acceleration of ball during highaav(h)m/s²—
acceleration of ball during fara(f)m/s²—
acceleration of ball during higha(h)m/s²—
x0≡xi(start of motion)
starting position
x≡xi(end of motion)
final position
v0≡vi(start of motion)
starting velocity
v≡vi(end of motion)
final velocity
t≡Δtm
time
A=Ax2+Ay2
magnitude from components
di(whole)=di(part 1)+di(part 2)
path in parts
Δtw=Δtp+Δtp
time in parts
ai(part 1)=ai(whole)
steady through its parts
vo,x(t)=vo(t)⋅cos⁡θo(t)
parts of a velocity
ai,x(m)=0
falling freely
R2=A2+B2+2⋅A⋅B⋅cos⁡φ
law of cosines
R⋅sin⁡β=B⋅sin⁡φ
law of sines
R⋅cos⁡β=A+B⋅cos⁡φ
along the first
Ax=A⋅cos⁡α
resolved along x
Ay=A⋅sin⁡α
resolved along y
Δxx(f)=xx(f₁)-xx(f₀)
change of position(far, x)
Δxy(f)=xy(f₁)-xy(f₀)
change of position(far, y)
Δxx(h)=xx(h₁)-xx(h₀)
change of position(high, x)
Δxy(h)=xy(h₁)-xy(h₀)
change of position(high, y)
vav,x(f)=Δxx(f)Δtf
displacement a time(far, x)
vav,y(f)=Δxy(f)Δtf
displacement a time(far, y)
vav,x(h)=Δxx(h)Δth
displacement a time(high, x)
vav,y(h)=Δxy(h)Δth
displacement a time(high, y)
cav(f)=d(f)Δtf
path a time(far, x)
cav(f)=d(f)Δtf
path a time(far, y)
cav(h)=d(h)Δth
path a time(high, x)
cav(h)=d(h)Δth
path a time(high, y)
Δvx(f)=vx(f₁)-vx(f₀)
velocity gained(far, x)
Δvy(f)=vy(f₁)-vy(f₀)
velocity gained(far, y)
Δvx(h)=vx(h₁)-vx(h₀)
velocity gained(high, x)
Δvy(h)=vy(h₁)-vy(h₀)
velocity gained(high, y)
aav,x(f)=Δvx(f)Δtf
velocity gained a time(far, x)
aav,y(f)=Δvy(f)Δtf
velocity gained a time(far, y)
aav,x(h)=Δvx(h)Δth
velocity gained a time(high, x)
aav,y(h)=Δvy(h)Δth
velocity gained a time(high, y)
vx(f₁)=vx(f₀)+ax(f)⋅Δtf
velocity after a time(far, x)
vy(f₁)=vy(f₀)+ay(f)⋅Δtf
velocity after a time(far, y)
vx(h₁)=vx(h₀)+ax(h)⋅Δth
velocity after a time(high, x)
vy(h₁)=vy(h₀)+ay(h)⋅Δth
velocity after a time(high, y)
xx(f₁)=xx(f₀)+vx(f₀)⋅Δtf+ax(f)⋅Δtf22
position after a time(far, x)
xy(f₁)=xy(f₀)+vy(f₀)⋅Δtf+ay(f)⋅Δtf22
position after a time(far, y)
xx(h₁)=xx(h₀)+vx(h₀)⋅Δth+ax(h)⋅Δth22
position after a time(high, x)
xy(h₁)=xy(h₀)+vy(h₀)⋅Δth+ay(h)⋅Δth22
position after a time(high, y)
vx(f₁)2=vx(f₀)2+2⋅ax(f)⋅(xx(f₁)-xx(f₀))
velocity after a distance(far, x)
vy(f₁)2=vy(f₀)2+2⋅ay(f)⋅(xy(f₁)-xy(f₀))
velocity after a distance(far, y)
vx(h₁)2=vx(h₀)2+2⋅ax(h)⋅(xx(h₁)-xx(h₀))
velocity after a distance(high, x)
vy(h₁)2=vy(h₀)2+2⋅ay(h)⋅(xy(h₁)-xy(h₀))
velocity after a distance(high, y)
xx(f₁)-xx(f₀)=(vx(f₁)+vx(f₀))⋅Δtf2
mean of the velocities(far, x)
xy(f₁)-xy(f₀)=(vy(f₁)+vy(f₀))⋅Δtf2
mean of the velocities(far, y)
xx(h₁)-xx(h₀)=(vx(h₁)+vx(h₀))⋅Δth2
mean of the velocities(high, x)
xy(h₁)-xy(h₀)=(vy(h₁)+vy(h₀))⋅Δth2
mean of the velocities(high, y)
vg,x(f₀)=vg(f₀)⋅cos⁡θg(f₀)
parts of a velocity(ground, start of far, x)
vg,y(f₀)=vg(f₀)⋅sin⁡θg(f₀)
parts of a velocity(ground, start of far, y)
vg,x(f₁)=vg(f₁)⋅cos⁡θg(f₁)
parts of a velocity(ground, end of far, x)
vg,y(f₁)=vg(f₁)⋅sin⁡θg(f₁)
parts of a velocity(ground, end of far, y)
vg,x(h₀)=vg(h₀)⋅cos⁡θg(h₀)
parts of a velocity(ground, start of high, x)
vg,y(h₀)=vg(h₀)⋅sin⁡θg(h₀)
parts of a velocity(ground, start of high, y)
vg,x(h₁)=vg(h₁)⋅cos⁡θg(h₁)
parts of a velocity(ground, end of high, x)
vg,y(h₁)=vg(h₁)⋅sin⁡θg(h₁)
parts of a velocity(ground, end of high, y)
vx(f₀)=v(f₀)⋅cos⁡θ(f₀)
parts of a velocity(ball, start of far, x)
vy(f₀)=v(f₀)⋅sin⁡θ(f₀)
parts of a velocity(ball, start of far, y)
vx(f₁)=v(f₁)⋅cos⁡θ(f₁)
parts of a velocity(ball, end of far, x)
vy(f₁)=v(f₁)⋅sin⁡θ(f₁)
parts of a velocity(ball, end of far, y)
vx(h₀)=v(h₀)⋅cos⁡θ(h₀)
parts of a velocity(ball, start of high, x)
vy(h₀)=v(h₀)⋅sin⁡θ(h₀)
parts of a velocity(ball, start of high, y)
vx(h₁)=v(h₁)⋅cos⁡θ(h₁)
parts of a velocity(ball, end of high, x)
vy(h₁)=v(h₁)⋅sin⁡θ(h₁)
parts of a velocity(ball, end of high, y)
ax(f)=0
falling freely(far, x)
ay(f)=−g
falling freely(far, y)
ax(h)=0
falling freely(high, x)
ay(h)=−g
falling freely(high, y)
Δx(f)=Δxx(f)2+Δxy(f)2
magnitude from components(displacement of ball during far)
x(f₁)=xx(f₁)2+xy(f₁)2
magnitude from components(position of ball at end of far)
x(f₀)=xx(f₀)2+xy(f₀)2
magnitude from components(position of ball at start of far)
Δx(h)=Δxx(h)2+Δxy(h)2
magnitude from components(displacement of ball during high)
x(h₁)=xx(h₁)2+xy(h₁)2
magnitude from components(position of ball at end of high)
x(h₀)=xx(h₀)2+xy(h₀)2
magnitude from components(position of ball at start of high)
vav(f)=vav,x(f)2+vav,y(f)2
magnitude from components(average velocity of ball during far)
vav(h)=vav,x(h)2+vav,y(h)2
magnitude from components(average velocity of ball during high)
Δv(f)=Δvx(f)2+Δvy(f)2
magnitude from components(change of velocity of ball during far)
v(f₁)=vx(f₁)2+vy(f₁)2
magnitude from components(velocity of ball at end of far from ground)
v(f₀)=vx(f₀)2+vy(f₀)2
magnitude from components(velocity of ball at start of far from ground)
Δv(h)=Δvx(h)2+Δvy(h)2
magnitude from components(change of velocity of ball during high)
v(h₁)=vx(h₁)2+vy(h₁)2
magnitude from components(velocity of ball at end of high from ground)
v(h₀)=vx(h₀)2+vy(h₀)2
magnitude from components(velocity of ball at start of high from ground)
aav(f)=aav,x(f)2+aav,y(f)2
magnitude from components(average acceleration of ball during far)
aav(h)=aav,x(h)2+aav,y(h)2
magnitude from components(average acceleration of ball during high)
a(f)=ax(f)2+ay(f)2
magnitude from components(acceleration of ball during far)
a(h)=ax(h)2+ay(h)2
magnitude from components(acceleration of ball during high)
vg(f₀)=vg,x(f₀)2+vg,y(f₀)2
magnitude from components(velocity of ground at start of far from ground)
vg(f₁)=vg,x(f₁)2+vg,y(f₁)2
magnitude from components(velocity of ground at end of far from ground)
vg(h₀)=vg,x(h₀)2+vg,y(h₀)2
magnitude from components(velocity of ground at start of high from ground)
vg(h₁)=vg,x(h₁)2+vg,y(h₁)2
magnitude from components(velocity of ground at end of high from ground)
v(h₀)=v(f₀)
the same ball