Salmon often jump waterfalls to reach their breeding grounds.
Starting downstream, 2.9 m away from a waterfall 0.436 m in height, at what minimum speed must a salmon jumping at an angle of 44.7◦ leave the water to continue upstream? The acceleration due to gravity is 9.81 m/s2 .

Respuesta :

Answer:

5.79 m/s

Explanation:

R=2.9 m

H=0.436 m

∅=44.7°

For Horizontal Motion

aₓ=0      uₓ=ucos∅

x=uₓt+[tex]\frac{1axt^{2} }{2}[/tex]

R=ucos∅*t+0

2.9=ucos(38.3)*t

t=[tex]\frac{4.079}{u}[/tex]

For Vertical Motion

Y=Uy*t+[tex]\frac{1ayt^{2} }{2}[/tex]

By putting value

0.436=usin∅([tex]\frac{4.079}{u}[/tex])-([tex]\frac{1}{2}g *(\frac{4.079}{u} )^{2}[/tex])

0.436=sin(44.7)([tex]\frac{4.079}[/tex])-([tex]\frac{1}{2}g *(\frac{4.079}{u} )^{2}[/tex])

0.436=2.869-[tex]\frac{81.61}{u^{2} }[/tex]

u²=33.54

u=5.79 m/s

Answer:

5.83 m/s

Explanation:

This is a projectile motion problem.

Let's call

[tex]V_0 [/tex] the initial velocity

In x-coordinate:

[tex]V_{0x} = V_0 \times cos \alpha [/tex]

where α is 44.7°

In y-coordinate:

[tex]V_{0y} = V_0 \times sin \alpha[/tex]

In x-coordinate the displacement is:

[tex]x = V_0 \times cos \alpha \times t [/tex]

where t is time. Isolating the initial speed and replacing with x = 2.9 (the distance travelled in x direction) :

[tex] V_0 = \frac{2.9}{cos \alpha \times t} [/tex]

In y-coordinate the displacement is:

[tex]y = V_0 \times sin \alpha \times t - 1/2 \times g \times t^2[/tex]

Replacing with the initial velocity, y = 0.436, alpha = 44.7° and g = 9.81:

[tex]0.436 = \frac{2.9}{cos \alpha \times t} \times sin \alpha \times t - 1/2 \times g \times t^2[/tex]

[tex]0.436 =2.9 \times tan 44.7 - 1/2 \times 9.81 \times t^2[/tex]

[tex] t^2 = \frac{2.9 \times tan 44.7 - 0.436}{ 1/2 \times 9.81} [/tex]

[tex]t = \sqrt{0.495}[/tex]

[tex]t = 0.7[/tex]

Replacing this value in the previous initial velocity equation:

[tex] V_0 = \frac{2.9}{cos 44.7 \times 0.7} [/tex]

[tex] V_0 = 5.83 \; m/s [/tex]