How can electric shock be prevented?

A uniform plank of mass 10kg and length 10m rests on two supports, A and B as shown. A boy of weight 500N stands at a distance o

kifflom [539]

Answer:

U² = 142.86 N

U¹ = 357.14 N

Explanation:

Taking summation of the moment about point A, we get the following equilibrium equation: (taking clockwise direction as positive)

$W(2\ m) - U^2(7\ m) = 0$

where,

W = weight of boy = 500 N

U² = reaction ay B = ?

Therefore,

$(500\ N)(2\ m)-(U^2)(7\ m)=0\\U^2=\frac{1000\ Nm}{7\ m}\\$

Now, taking summation of forces on the plank. Taking upward direction as positive, for equilibrium position:

$W-U^1-U^2=0\\500\ N - 142.86\ N = U^1\\$

3 0

3 years ago

g Calculate the maximum wavelength of light that will cause the photoelectric effect for potassium. Potassium has work function

Ivahew [28]

Answer:

λ = 5.4196 10⁻⁷m, λ = 541.96 nm this is green ligh

Explanation:

The photoelectric effect was explained by Eintein assuming that the light was made up of particles called photons and these collided with the electrons taking them out of the material.

K = h f -Ф

where K is the kinetic energy of the ejected electrons, hf is the energy of the light quanta and fi is the work function of the material.

The speed of light is related to wavelength and frequency

c = λ / f

f = c /λ

we substitute

K = h c / λ - Φ

for the case that they ask us the kinetic energy of the electons is zero (K = 0)

h c / λ = Ф

λ = h c / Ф

we calculate

λ = 6.63 10⁻³⁴ 3 10⁸ / 3.67 10⁻¹⁸

λ = 5.4196 10⁻⁷m

let's take nm

lam = 541.96 nm

this is green light

4 0

3 years ago

How are the oscillating magnetic and electric fields of an electromagnetic wave positioned relative to each other?

Pepsi [2]

Answer:

Electromagnetic waves consist of both electric and magnetic field waves. These waves oscillate in perpendicular planes with respect to each other, and are in phase. The creation of all electromagnetic waves begins with an oscillating charged particle, which creates oscillating electric and magnetic fields.

Explanation:

7 0

2 years ago

Hi!! Please Answer this question, & it would be AWESOME, LIKE REALLLYY AWESOME If you could send me a picture with the graph

scoray [572]

Answer:

Is there a map of the town? It doesn't make sense without coridnates or street lengths. If it was a straight isosilese triangles the return time is 3:36pm. This answer doesn't make sense if there is a map.

Explanation:

Side a is 12km Side b 15 km Side c 19.21 km.

9am depearture

11am 12km away rest

11:30am starts at 10 km/h

1:00 pm reaches town

2:00pm done lunch

3:36 pm return home.

3 0

2 years ago

There is a plate with moment of inertia Ip = 0.0711 kgm2 , rotating around its center of mass with angular speed of 4.53 rad/s.

Anna007 [38]

Answer:

1) their common angular speed = 3.038 rad/s

2) kinetic energy loss = 0.24J

Explanation:

1) This is a case of conservation of angular momentum.

The initial angular momentum must be equal to the final angular momentum

Initial angular momentum = I x w

Where I = moment of inertia, and

w = angular momentum.

Initial angular momentum = 0.0711 x 4.53 = 0.322 kg-m2-rad/s

After addition of ring, moment of inertia becomes,

0.0711 + 0.0353 = 0.106 kg-m2

Therefore, final angular momentum will be

0.106 x Wf

Where Wf = final common angular velocity

Equating the two angular momentum we have

0.322 = 0.106Wf

Wf = 0.322/0.106 = 3.038 rad/s

2) KE = 1/2 x I x w^2

Initial KE = 1/2 x 0.0711 x 4.53^2

= 0.729 J

Final KE = 1/2 x 0.106 x 3.038^2

= 0.489 J

Loss in KE = 0.729 - 0.489 = 0.24 J

5 0

3 years ago