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3 years ago

A cable that weighs 4 lb/ft is used to lift 1000 lb of coal up a mine shaft 700 ft deep. Find the work done.

Physics

1 answer:

Shkiper50 [21]3 years ago

6 0

Answer:

Explanation:

Step one:

given data

mass of cable= 4lb/ft

mass of coal= 1000lb

dept of mine= 700ft

Step two:

Required

the work-done to lift the coal and the rope combined

Work-done to lift coal

Wc=1000*700= 700,000 lb-ft

Work-done to lift rope

$Wr=\int\limits^{700} _0 {4(700-y)} \, dx \\\\Wr=4(700y-\frac{1}{2}y^2 )\limits^{700}_0$

substitute y=700 we have, since y=0 will result to 0

$Wr=4(700*700-\frac{1}{2}*700^2 )\\\\Wr=4(490000-245000)\\\\Wr=4(245000)\\\\Wr=980000ft-lbs$

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Answer:

B. Newton's second law of motion

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Please help me with this question. BRAINLIEST if answered.

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3 years ago

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3 years ago

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4 years ago

The electric field of a sinusoidal electromagnetic wave obeys the equation E=(375V/m)cos[(1.99×107rad/m)x+(5.97×1015rad/s)t].a.

andrey2020 [161]

Answer:

A) max = Eo = 375 V/m, B) B = 125 10⁻⁸ T , C) f = 9.50 101⁴ Hz, D) λ = 3.158 10⁻⁷ m, E) T = 1.05 10⁻¹⁵ s , F) invisible for humans G) v = c = 3 10⁸ m/s

Explanation:

The expression given for the electric field is

E = 375 cos (1.99 107x + 5.97 105t)

The general formula for the electric field of a transverse traveler is

E = Eo cos (kx-wt)

Where k is the wave number and w the angular velocity

A) The amplitudes as electric is

Emax = Eo = 375 V / m

B) the electric and magnetic field are related

E / B = c

B = E / c

B = 375/3 108

B = 125 10⁻⁸ T

C) angular velocity and frequency is related

.w = 2π f

f = w / 2π

f = 5.97 10¹⁵ / 2π

f = 9.50 101⁴ Hz

D) the speed of light has the formula

c = λ f

λ = c / f

λ = 3 10⁸ / 9.50 10¹⁴

λ = 3.158 10⁻⁷ m

E) The period

T = 1 / f

T = 1 / 9.5 10¹⁴

T = 1.05 10⁻¹⁵ s

F) let's reduce the wavelength nm

λ = 3.158 10⁻⁷ m (10⁹nm / 1m)

λ = 3.158 10²nm = 315.3 nm

The visible radiation range is between 400nm and 700nm. This radiation is ultraviolet and is invisible humans

G) All electromagnetic radiation has a speed at the speed of light (c)

v = c = 3 10⁸ m/s

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3 years ago