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Aliun [14]
3 years ago
10

You and your friend Peter are putting new shingles on a roof pitched at 21∘. You're sitting on the very top of the roof when Pet

er, who is on the edge of the roof, 5.1 mm away, asks you for the box of nails. Rather than carry the 2.3 kgkg box of nails down to Peter, you decide to give the box a push and have it slide down to him. If the coefficient of kinetic friction between the box and the roof is 0.53, with what speed should you push the box to have it gently come to rest right at the edge of the roof?
Physics
1 answer:
Marat540 [252]3 years ago
8 0

Answer:

3.69 m/s

Explanation:

Forces :

mgsin Θ - mumgcosΘ = ma  

g x sinΘ  - mu x g x cosΘ  = a

9.8 x sin 21 - 0.53 x 9.8 x cos 21 = a

a = -1.337 m/s²

so you have final velocity = 0 m/s

initial velocity = ? m/s

Given d = 5.1 m

By kinematics

vf² = vo² + 2ad

0 = vo² + 2 x -1.337*5.1

vo = 3.69 m/s

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Que es la accion y reaccion
alina1380 [7]

Answer:

what is the action and reaction ?

Explanation:

   

4 0
3 years ago
The gnaphosid spider Drassodes cupreus has evolved a pair of lensless eyes for detecting polarized light. Each eye is sensitive
BartSMP [9]

Answer:

Part A

The intensity is  I = 618 W/m^2  

Part B

The intensity is  I_1= 81.884 W/m^2

Explanation:

From the question we are told that

       The intensity of the light detected by first eye is I = 700 W/m^2

Now at initial state according the question the light  ray is perpendicular to the eye so it means that it is at 90° the eye

Now the first question is to obtain the intensity the first eye (the first in this case is the one focused on the light  )would detect when the head is rotated by 20°  its previous orientation

This  is mathematically evaluated  as

                   I = I_i cos^2 ( 20^o)

                    I = 700\  cos^2 (20)

                    I = 618 W/m^2  

Now the second  question is to obtain the intensity the first eye (the first eye  in this case is the one that is not  focused on  the light  )would detect when the head is rotated by 20°  its previous orientation

Now in this case the angle between the eye and the light is 90-20 = 70°

           So

               I_1 = 700 \  cos^2 (70)

                   I_1= 81.884 W/m^2

 

5 0
2 years ago
An electron is initially at rest in a uniform electric field having a strength of 1.85 × 106 V/m. It is then released and accele
kirza4 [7]

Answer:

W = 462.5 keV

Explanation:

As we know that when electron moved in electric field then work done by electric field must be equal to the change in kinetic energy of the electron

So here we have to find the work done by electric field on moving electron

So we have

F = qE

F = (1.6 \times 10^{-19})(1.85 \times 10^6)

F = 2.96 \times 10^{-13} N

now the distance moved by the electron is given as

d = 0.25 m

so we have

W = F.d

W = (1.6 \times 10^{-19})(1.85 \times 10^6)(0.25)

W = 7.4 \times 10^{-14} J

now we have to convert it into keV units

so we have

1 keV = 1.6 \times 10^{-16} J

W = 462.5 keV

5 0
3 years ago
A tetrahedron has an equilateral triangle base with 25.0-cm-long edges and three equilateral triangle sides. The base is paralle
djverab [1.8K]

Answer:

a. 7.046 Nm²/C

b. 2.348 Nm²/C

Explanation:

Data given:

Base of equilateral triangle = 25.0 cm = 0.25 m

Strength of electric field = 260 N/C

In order to find the electric flux we first have to find out the area of triangle.

Area of triangle = \frac{\sqrt{3} }{4} a^{2}

                         = \frac{\sqrt{3} }{4} (0.25)^{2}

                         = 0.0271 m³

Lets find electric flux,

      Electric Flux = E. A

                          = 260×0.0271

                          = 7.046 Nm²/C

Now we can find the electric flux through each of the three sides.

Electric flux through three sides = \frac{7.046}{3}

                                                = 2.348 N m²/C

       

3 0
3 years ago
sest yourse 1. A pencil lies on the dashboard of a car. a) i) What happens to the pencil when the car suddenly stops? suddenly a
julia-pushkina [17]

Answer:

1. the pencil would have the momentum and would keep going until it hits the windshield. 2. when the car suddenly accelerates, the pencil would be inert and it would move toward the back of the car until a constant speed from the car is reached.

8 0
2 years ago
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