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malfutka [58]
3 years ago
8

From what height should you drop a ball so that it hits the ground at 40 m/s? How long will it take to hit the ground?

Physics
1 answer:
Ksenya-84 [330]3 years ago
7 0

Explanation:

It is given that,

A ball hits the ground at 40 m/s

Let h is the height from where you drop a ball. It is based on the conservation of energy as :

mgh=\dfrac{1}{2}mv^2\\\\h=\dfrac{v^2}{2g}\\\\\text{Putting all the values in above formula}\\\\h=\dfrac{40^2}{2\times 9.8}\\\\h=81.63\ m

It is dropped from a height of 81.63 m.

Let it take t seconds to hit the ground. When it hits the ground, its final speed, v = 0 and u = 40 m/s. So,

h=ut+\dfrac{1}{2}gt^2\\\\h=\dfrac{1}{2}gt^2\\\\t=(\dfrac{2h}{g})^{1/2}\\\\t=(\dfrac{2\times 81.63}{9.8})^{1/2}\\\\t=4.08\ s

So, it will take 4.08 seconds to hit the ground.

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Categorize each ray tracing statement as relating to ray 1, ray 2, or ray 3.
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Answer:

statement 1 with answer C

statement 2 with answer F

statement 3 with answer B

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Statement 2 with A

Statement 3 with D

Explanation:

In this exercise you are asked to relate each with the answers

In general, in the optics diagram,

* Ray 1 is a horizontal ray that after stopping by the optical system goes to the focal point

* Ray 2 is a ray that passes through the intercept point between the optical axis and the system and does not deviate

* Ray 3 is a ray that passes through the focal length and after passing the optical system, it comes out horizontally.

With these statements, let's review the answers

statement 1 with answer C

statement 2 with answer F

statement 3 with answer B

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3 years ago
A football is kicked into the air from an initial height of 4 feet. The height, in feet, of the football above the ground is giv
kakasveta [241]

Answer: 0.5 seconds or 2.625 seconds

Explanation:

At t = 0, The ball is 4 ft above the ground.

The height of the football varies with time in the following way:

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⇒25 = -16 t² + 50 t + 4

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Therefore, at t = 0.5 s or 2.625 s, the football would be 25 ft above the ground.

3 0
3 years ago
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den301095 [7]

Answer:

The elements in the reactants are the same as the elements in the products

Explanation:

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The resistivity of the material of a wire is 1. 76 × 10-8 ωm. if the diameter of the wire is 2 × 10-3 m and its length is 2 m, then its resistance is  0.0112Ω

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It does not alter as the wire length increases, but resistance increases fourfold when the wire is stretched to double its original length. Resistivity is defined as the electrical resistance per unit length and cross-sectional area of a conductor.

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they need the Sun's energy in order to produce food <span>
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