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2 years ago

In which scenario is an animal doing work? Check all that apply.

Physics

2 answers:

sveta [45]2 years ago

9 0

Its 1,3, and 5. just took quiz and got it right.

Likurg_2 [28]2 years ago

9 0

A cat lifts up her kitten by its neck.

A bird carries a worm to its nest.

A horse pulls a wagon along a road.

Explanation:

Work is defined as the product between the force applied to an object and the distance the object has been moved:

$W=Fd$

therefore, work is non-zero only if the object has been moved by a distance different from zero. This is exactly what happens in the three following scenarios:

A cat lifts up her kitten by its neck.

A bird carries a worm to its nest.

A horse pulls a wagon along a road.

In all these cases, an object (the kitten, the nest and the wagon) are moved through a certain distance, so work is done. On the contrary, in the other two examples:

A dog rubs his back against a large tree

A goat butts its head against the barn wall.

No object is moved, so d=0 in the formula and no work is done.

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A sleeping 68 kg man has a metabolic power of 79 w .

Lesechka [4]

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2 years ago

Two of the types of ultraviolet light, uva and uvb, are both components of sunlight. their wavelengths range from 320 to 400 nm

a_sh-v [17]

In light energy, the higher the frequency, the greater the energy a light contain.

We know for a certain that frequency is just the reciprocal of wavelength:

frequency = 1 / wavelength

Calculating for frequencies:

f UVA = 1/320 to 1/400

f UVA = 0.0031 to 0.0025

f UVB = 1/290 to 1/320

f UVB = 0.0034 to 0.0031

Since UVB has higher frequency range, then it has higher energy than UVA.

7 0

2 years ago

Read 2 more answers

Water at 20°C flows by gravity through a smooth pipe from one reservoir to a lower one. The elevation difference is 60 m. The pi

Serga [27]

Answer:

Flow Rate = 80 m^3 /hours (Rounded to the nearest whole number)

Explanation:

Given

Hf = head loss
f = friction factor
L = Length of the pipe = 360 m
V = Flow velocity, m/s
D = Pipe diameter = 0.12 m
g = Gravitational acceleration, m/s^2
Re = Reynolds's Number
rho = Density =998 kg/m^3
μ = Viscosity = 0.001 kg/m-s
Z = Elevation Difference = 60 m

Calculations

Moody friction loss in the pipe = Hf = (f*L*V^2)/(2*D*g)

The energy equation for this system will be,

Hp = Z + Hf

The other three equations to solve the above equations are:

Re = (rho*V*D)/ μ

Flow Rate, Q = V*(pi/4)*D^2

Power = 15000 W = rho*g*Q*Hp

1/f^0.5 = 2*log ((Re*f^0.5)/2.51)

We can iterate the 5 equations to find f and solve them to find the values of:

Re = 235000

f = 0.015

V = 1.97 m/s

And use them to find the flow rate,

Q = V*(pi/4)*D^2

Q = (1.97)*(pi/4)*(0.12)^2 = 0.022 m^3/s = 80 m^3 /hours

7 0

2 years ago

A 12-V DC automobile head lamp is to be used on a fishing boat with a 24-V power system. The head lamp is rated at 50 W. A resis

spin [16.1K]

Answer:

The resistance is $R = 2.88 \ \Omega$

Explanation:

From the question we are told that

The voltage rating of the headlamp is $V_1 = 12 \ V$

The voltage of the power system is $p = 24 \ V$

The power rating of the headlamp is $P = 50 W$

Generally the power which the resistor dissipates is mathematically represented as

$P = V_L * I$

=> $50 = 12 * I$

=> $I = 4.1667 \ A$

Generally the resistance is

$R = \frac{V_1 }{I}$

$R = \frac{12 }{4.1667}$

$R = 2.88 \ \Omega$

8 0

2 years ago

A light wave has a 670 nm wavelength in air. Its wavelength in a transparent solid is 420 nm.

zhuklara [117]

Answer: speed of light in solid = 1.88 * 10^8 m/s

Frequency is constant

Explanation: The relationship between the velocity of light wave and wavelength is given by the formulae below

V = fλ

During refraction, the frequency of light is constant, thus we have that

V = kλ which implies that velocity is proportional to wavelength.

Hence, we have that

v1/ λ1 = v2/ λ2

Where v1 = velocity of light in air = 3 * 10^8 m/s

v2 = velocity of sound in solid

λ1 = wavelength of light in air = 670nm

λ2 = wavelength of light in solid = 420nm

By making v2 subject of formulae, we have that

v2 = v1 * λ2/ λ1

v2 = 3 * 10^8 * 420nm/ 670nm

v2 = 3 * 10^8 * 0.6268

v2 = 1.88 * 10 ^8 m/s

During refraction the frequency of light wave is constant this is because light consist of photons which has energy. it energy needs to be constant and for energy (E=hf) to be constant, frequency would be constant too.

4 0

2 years ago