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marshall27 [118]

4 years ago

11

The alarm at a fire station rings and an 86-kg fireman, starting from rest, slides down a pole to the floor below (a distance of

4.0 m). just before landing, his speed is 1.4 m/s. what is the magnitude of the kinetic frictional force exerted on the fireman as he slides down the pole?

1 answer:

xenn [34]4 years ago

8 0

<span>Vf^2=Vi^2+2ad you know Vf, Vi, mg, and distance d. solve for frictionforceResponding to an alarm, a 100 kg, a fireman slides down a pole to the ground floor, 3.1 m below. The fireman starts at rest and lands with a speed of 3.8 m/s. Find the average force exerted on the fireman by the pole. Find the average force exerted on the fireman when the landing speed is 1.9 m/s.</span>

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4 years ago

Suppose that a parallel-plate capacitor has circular plates with radius R = 25 mm and a plate separation of 4.7 mm. Suppose also

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Answer:

a) $B_{max} = 1.784*10^{-12}$

Explanation:

Given paraeters are:

R = 25 cm

d = 4.7 mm

f = 60 Hz

$V_m$ = 160 V

a) $V = V_msin(2\pi ft)$

Where $f = 60$ Hz and $V_m = 160$ V

$E =V/d= \frac{V_msin(2\pi ft)}{d}$

For $r = R$

$A = \pi R^2$

Since $\Phi_E = EA$

$\Phi_E=\frac{\pi R^2V_msin(2\pi ft) }{d}$

From Ampere's Law:

$\int B.ds = \mu_0\epsilon_0\frac{d\Phi_E}{dt} + \mu_0I_{encl}$ where $I_{encl}=0$

So at $r = R$ ,

$B.2\pi R = \mu_0\epsilon_0\frac{d\Phi_E}{dt}\\B.2\pi R = \mu_0\epsilon_0\frac{2\pi^2fR^2V_mcos(2\pi ft)}{d}\\B = \frac{\mu_0\epsilon_0\pi fRV_mcos(2\pi ft)}{d}$

For maximum B, cos(2πft) = 1. Hence,

$B_{max}=\frac{\mu_0\epsilon_0\pi fRV_m}{d}=\frac{4\pi*10^{-7}*8.85*10^{-12}*\pi*60*0.025*160}{4.7*10^{-3}}=1.784*10^{-12}$ T

b) From r = 0 to r = R = 0.025 m, by Ampere's Law, the equation will be:

$B = \frac{\mu_0\epsilon_0\pi fR^2V_m}{rd}$

From r = R = 0.025 m to r = 0.1 m, by Ampere's Law, the equation will be:

$B = \frac{\mu_0\epsilon_0\pi fRV_m}{d}$

The plot is given in the attachment.

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4 years ago

when the color purple is reflected off a hat, what can we say is happening to the light waves?

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That every wave length of light except purple is being absorbed by the hat. The hat will be the color purple

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3 years ago

Read 2 more answers

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3 years ago