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ollegr [7]
3 years ago
8

You are throwing a stone straight-up in the absence of air friction. The stone is caught at the same height from which it was th

rown. the speed of the stone when thrown is equal to the speed when caught.A. TrueB. False
Physics
1 answer:
balu736 [363]3 years ago
7 0

Answer:

A. True

Explanation:

When a stone is thrown straight-up, it has an initial velocity which decreases gradually as the stone move to maximum height due to constant acceleration due to gravity acting downward on the stone, at the maximum height the final velocity of the stone is zero. As the stone descends the velocity starts to increase and becomes maximum  before it hits the ground.

Height of the motion is given by;

H = \frac{u^2}{2g}

g is acceleration due to gravity which is constant

H is height traveled

u is the speed of throw, which determines the value of height traveled.

Therefore, when the stone is caught at the same height from which it was thrown in the absence of air resistance, the speed of the stone when thrown will be equal to the speed when caught.

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Two long, parallel wires are separated by 2.2 mm. Each wire has a 32-AA current, but the currents are in opposite directions. Pa
Alex

Answer:

B=1.1636*10^{-3}T

Explanation:

Given data

d_{wires}=2.2mm=0.022m\\ I_{current}=32A\\

To find

Magnitude of the net magnetic field B

Solution

The magnitude of the net magnetic field can be find as:

B=2*u\frac{I}{2\pi r}\\ B=2*(4\pi*10^{-7}  )\frac{32}{2\pi (0.022/2)} \\ B=1.1636*10^{-3}T

3 0
3 years ago
Telephone signals are often transmitted over long distances by microwaves. What is the frequency of microwave radiation with a w
amm1812

Answer:

1) f= 8.6 GHz

2) t= 0.2 ms

Explanation:

1)

  • Since microwaves are electromagnetic waves, they move at the same speed as the light in vacuum, i.e. 3*10⁸ m/s.
  • There exists a fixed relationship between the frequency (f) , the wavelength (λ) and the propagation speed in any wave, as follows:

        v = \lambda * f (1)

  • Replacing by the givens, and solving for f, we get:

       f =\frac{c}{\lambda} =\frac{3e8m/s}{0.035m} = 8.57e9 Hz (2)

⇒     f = 8.6 Ghz (with two significative figures)

2)

  • Assuming that the microwaves travel at a constant speed in a straight line (behaving like rays) , we can apply the definition of average velocity, as follows:

       v =\frac{d}{t} (3)

       where v= c= speed of light in vacuum = 3*10⁸ m/s

       d= distance between mountaintops = 52 km = 52*10³ m

  • Solving for t, we get:

       t = \frac{d}{c} = \frac{52e3m}{3e8m/s} = 17.3e-5 sec = 0.173e-3 sec = 0.173 ms (4)

       ⇒  t = 0.2 ms (with two significative figures)

6 0
3 years ago
Vector sum of 15 m, East and 9 m, West is 24 m, East. True False
Firlakuza [10]

Answer:

False

Explanation:

Because when you go through east

( +x axis ) then you go to west ( -x axis )

You will subtract -9 from +15

it's become +6

( I talk about the displacement not distance) ( West = - East )

I hope that it's a clear ") .

7 0
3 years ago
Read 2 more answers
Three point charges are placed on the y-axis: a charge q at y=a, a charge –2q at the origin, and a charge q at y= –a. Such an ar
den301095 [7]

Answer:

electric field   Et = kq [1 / (x-a)² -2 / x² + 1 / (x+a)²]

Explanation:

The electric field is a vector, so it must be added as vectors, in this problem both the charges and the calculation point are on the same x-axis so we can work in a single dimension, remembering that the test charge is always positive whereby the direction of the field will depend on the load under analysis, if the field is positive, if the field is negative.

 a) Let's write the electric field for each charge and the total field

       E = k q /r

With k the Coulomb constant, q the charge and r the distance of the charge to the test point

       Et = E1 + E2 + E3

       E1 = k q / (x-a)²

       E2 = k (-2q) / x²  

       E3 = k q / (x + a)²

       Et = kq [1 / (x-a)² -2 / x² + 1 / (x+a)²]

The direction of the field is along the x axis

b) To use a binomial expansion we must have an expression the form (1-x)⁻ⁿ  where x << 1, for this we take factor like x from all the equations

       Et = kq/ x² [1 / (1-a/x)² - 2 + 1 / (1+a/x)²]

We use binomial expansion

     (1+x)⁻² = 1 -nx + n (n-1) 2! x² +… x << 1

     (1-x)⁻² = 1 +nx + n (n-1) 2! x² + ...

They replace in the total field and leaving only the first terms

       

   Et =kq/x² [-2 +(1 +2 a/x + 2 (2-1)/2 (a/x)² +…) + (1 -2 a/x + 2(2-1) /2 (a/x)² +.) ]

   Et = kq/x² [a²/x² + a²/x²2] = kq /x² [2 a²/x²]

Et = k q 2a²/x⁴

point charge

Et = k q 1/x²

Dipole

E = k q a/x³

3 0
3 years ago
PLEASE HELP: Why are shooting stars bright?
mrs_skeptik [129]

the answer is c I hope this helps

4 0
3 years ago
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