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faust18 [17]
3 years ago
15

American eels (Anguilla rostrata) are freshwater fish with long, slender bodies that we can treat as a uniform cylinder 1.0 m lo

ng and 10 cm in diameter. An eel compensates for its small jaw and teeth by holding onto prey with its mouth and then rapidly spinning its body around its long axis to tear off a piece of esh. Eels have been recorded to spin at up to 14 rev/s when feeding in this way. Although this feeding method is energetically costly, it allows the eel to feed on larger prey than it otherwise could.An eel researcher uses the slow-motion feature on her phone's camera to shoot a video of an eel spinning at its maximum rate. The camera records at 120 frames per second. Through what angle does the eel rotate from one frame to the next?A. 1° B. 10° C. 22° D. 42°
Physics
1 answer:
madam [21]3 years ago
4 0

Answer:

option D

Explanation:

given,

uniform length of cylinder = 1 m

diameter of the cylinder = 10 cm = 0.1 m

Eels have been recorded to spin = 14 rev/s

camera records at = 120 frames per second

time = \dfrac{1}{120}\ s/frame

angle at which eel rotate = ?

ω = 14 rev/s

ω = 14 x 2 π rad/s

ω = 28 π rad/s

angle at which eel rotate

 θ = ω t

θ = 28\pi\times \dfrac{1}{120}

θ = 0.733 rad

θ =0.733 \times \dfrac{180^0}{2\pi}

θ =42^0

Hence, the correct answer is option D

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A piece of toast weighing 8 grams is flying through the air at 15
Ket [755]

The kinetic energy of toast is 0.06 J.

<u>Explanation:</u>

Kinetic energy is the way to determine the energy released when an object is in motion. In other times, it can be the energy required to move any object and to make it in motion.

As the mass of the toast is given as 8 g and speed is given as 15 m/s, if we ignore the friction caused by air molecules. Then the kinetic energy is the product of mass and square of velocity.

K.E. = \frac{1}{2} × mass × v²

Kinetic energy =\frac{1}{2} \times \frac{8}{1000} \times 15

Since, the weight is given in grams , it needed to be converted into kg.

Kinetic energy = 0.06 J

Thus, the kinetic energy of toast is 0.06 J.

6 0
3 years ago
A 1 m long wire of diameter 1mm is submerged in an oil bath of temperature 25-degC. The wire has an electrical resistance per un
Zarrin [17]

Answer:

steady state temperature =88.7deg C

t=time within  1 deg C of it steady state is 8.31s

Explanation:

A 1 m long wire of diameter 1mm is submerged in an oil bath of temperature 25-degC. The wire has an electrical resistance per unit length of 0.01 Ω/m. If a current of 100 A flows through the wire and the convection coefficient is 500W/m2K, what is the steady state temperature of the wire? From the time the current is applied, how long does it take for the wire to reach a temperature within 1-degC of the steady state value? The density of the wire is 8,000kg/m3, its heat capacity is 500 J/kgK and its thermal condu

The diameter of the wire is known to be=1mm

properties=

The density of the wire is 8,000 kg/m3,

heat capacity is 500 J/kgK

themal conductivity is 20W/m.K

electrical resistance per unit length of 0.01 Ω/m

from lump capavity method

B_{i} =\frac{hr/2}{k}

500*(2.5*10^-4)/20

0.006<0.1

we know also, to find steady state temperature

\piDh(T-Tinf)=I^{2} R_{e}

make T the subject of the equation , we have

T=25+\frac{100^2*0.01}{\pi*0.001*500 }

T=88.7 degC

rate of chnage in temperature

dT/dt=\frac{I^2*Re}{rho*c*\pi*D^2/4 } -\frac{4h}{rho*c*D} (T-Tinf)

at t=o and integrating both sides\frac{T-Tinf-(I^2*Re/\pi*Dh) }{Ti-Tinf-(I^2*Re/\pi*Dh } =exp\frac{-4ht}{rho*c*D}

we have

\frac{87.7-25-63.7}{25-25-63.7} =exp\frac{4*500t}{8000*500*0.001}

t=8.31s

steady state temperature =88.7deg C

t=time within  1 degC of it steady stae is 8.31s

7 0
3 years ago
What rapid changes to earths surface are caused by shifting plates
PtichkaEL [24]
I am not sure if this is the answer you are looking for but a earthquake occurs when the plates shift. 
Hope this helped. 
4 0
3 years ago
The deepest point in the ocean is 11 km below sea level, deeper than Mt. Everest is tall.
34kurt

The pressure at the depth 11 km below sea level can be calculated using

P=ρgh

P is pressure, ρ is the density of the fluid; g is the gravitational constant, h is the height from the surface, or depth that the object is submerged.

P = ( 1000 kg/ m3) ( 9.81 m.s2)( 11 000m) + 1 atm

P = 107,910,000 pa ( 1 atm/ 101 325 Pa) + 1 atm = 1066 atm

8 0
3 years ago
In pairs figure-skating competition, a 65-kg man and his 45-kg female partner stand facing each other both at rest on the ice. I
Lina20 [59]

Answer:

The final velocity of her partner is approximately -1.04 m/s or 1.04 m/s in the opposite direction to her direction of motion

Explanation:

The given parameters are;

The mass of the man, m₁ = 65 kg

The mass of the woman, m₂ = 45 kg

Taking the relative initial velocity of the man and the woman as 0 m/s, we have;

The initial velocity of the man, v₁₁ = 0 m/s

The initial velocity of the man, v₁₂ = 0 m/s

The final velocity of the woman, v₂₂ = 1.5 m/s

The final velocity of the man = v₂₁

Therefore, we have, by the conservation of momentum principle;

The total initial momentum = The total final momentum

Which gives;

m₁ × v₁₁ + m₂ × v₁₂ = m₁ × v₂₁ + m₂ × v₂₂

Substituting the known values;

65 × 0 + 45 × 0 = 65 × v₂₁ + 45 × 1.5

∴ 65 × v₂₁ + 45 × 1.5 = 0

45 × 1.5 = - 65 × v₂₁

v₂₁ = 45 × 1.5/(-65) ≈ -1.04 m/s

The final velocity of the man, her partner = v₂₁ ≈ -1.04 m/s.

6 0
3 years ago
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