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3 years ago

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A man throws a ball vertically upward with an initial speed of 20m/s. What is the maximum height reached by the ball and how lon

g does it take to return to the point it was thrown?

1 answer:

Luba_88 [7]3 years ago

8 0

Answer:

It's your first question!!!

Explanation:

Enjoy it!!!

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A positive kaon (K+) has a rest mass of 494 MeV/c² , whereas a proton has a rest mass of 938 MeV/c². If a kaon has a total energ

vitfil [10]

Answer:

<em>0.85c </em>

Explanation:

Rest mass of Kaon $M_{0K}$ = 494 MeV/c²

Rest mass of proton $M_{0P}$ = 938 MeV/c²

The rest energy is gotten by multiplying the rest mass by the square of the speed of light c²

for the kaon, rest energy $E_{0K}$ = 494c² MeV

for the proton, rest energy $E_{0P}$ = 938c² MeV

Recall that the rest energy, and the total energy are related by..

$E$ = γ $E_{0}$

which can be written in this case as

$E_{K}$ = γ $E_{0K}$ ...... equ 1

where $E$ = total energy of the kaon, and

$E_{0}$ = rest energy of the kaon

γ = relativistic factor = $\frac{1}{\sqrt{1 - \beta ^{2} } }$

where $\beta = \frac{v}{c}$

But, it is stated that the total energy of the kaon is equal to the rest mass of the proton or its equivalent rest energy, therefore...

$E_{K}$ = $E_{0P}$ ......equ 2

where $E_{K}$ is the total energy of the kaon, and

$E_{0P}$ is the rest energy of the proton.

From $E_{K}$ = $E_{0P}$ = 938c²

equ 1 becomes

938c² = γ494c²

γ = 938c²/494c² = 1.89

γ = $\frac{1}{\sqrt{1 - \beta ^{2} } }$ = 1.89

1.89 $\sqrt{1 - \beta ^{2} }$ = 1

squaring both sides, we get

3.57( 1 - $\beta^{2}$ ) = 1

3.57 - 3.57 $\beta^{2}$ = 1

2.57 = 3.57 $\beta^{2}$

$\beta^{2}$ = 2.57/3.57 = 0.72

$\beta = \sqrt{0.72}$ = 0.85

but, $\beta = \frac{v}{c}$

v/c = 0.85

v = <em>0.85c </em>

7 0

3 years ago

A bolt is dropped from a bridge under construction, falling 96 m to the valley below the bridge. (a) How much time does it take

irakobra [83]

Answer:

a)It takes the bolt 0.25 s to pass the last 11% of the fall.

b)When the bolt begins to fall the last 11% of the fall its velocity is -41.2 m/s.

c)The velocity of the bolt just before it reaches the ground is -43.6 m/s

Explanation:

Hi there!

a) Let´s calculate how much distance it is the last 11% of the fall:

96 m · 0.11 = 10.56 m

So, we have to find how much time it takes the bolt to pass from a height of 10.56 m to the ground.

First, let´s calculate how much time it takes the bolt to reach a height of 10.56 m. For that we can use this equation:

h = h0 + v0 · t + 1/2 · g · t²

Where:

h = height of the bolt at a time t.

h0 = initial height.

v0 = initial velocity.

t = time.

g = acceleration due to gravity.

If we consider the ground as the origin of the frame of reference, then h0 = 96 m. Since the bolt is dropped, the initial velocity is zero (v0 = 0). Then, the equation gets reduce to this:

h = h0 + 1/2 · g · t²

We have to find at which time h = 10.56 m.

10.56 m = 96 m - 1/2 · 9.8 m/s² · t²

Solving for t:

√(-2 · (10.56 m - 96 m) / 9.8 m/s²) = t

t = 4.2 s

Now that we have the time at which the bolt is located at 10.56 m above the ground, we can calculate the velocity of the bolt at that time.

The equation of velocity (v) of the bolt is the following:

v = v0 + g · t

at t = 4.2 s.

v = 0 - 9.8 m/s² · 4.2 s

v = -41.2 m/s

<u>When the bolt begins to fall the last 11% of the fall its velocity is -41.2 m/s.</u>

Now, we can calculate how much time it takes to fall the last 10.56 m.

The initial velocity of the bolt will be the velocity at h = 10.56 m. The initial height will be 10.56 m.

h = h0 + v0 · t + 1/2 · g · t²

We have to find the time at which h = 0 (the bolt hits the ground)

0 = 10.56 m - 41.2 m/s · t - 1/2 · 9.8 m/s² · t²

Solving the quadratic equation using the quadratic formula:

t = 0.25 s (the other solution of the quadratic equation is negative and thus discarded).

<u>It takes the bolt 0.25 s to pass the last 11% of the fall.</u>

Now, let´s calculate the velocity of the bolt when it reaches the ground:

v = v0 + g · t

v = -41.2 m/s - 9.8 m/s² · 0.25 s

v = -43.6 m/s

<u>The velocity of the bolt just before it reaches the bolt is -43.6 m/s</u>

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3 years ago

The sun is located in

Fiesta28 [93]

Milky Way Galaxy, same one as you.

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A)what are oxidation numbers? b) what useful functions do oxidation numbers serve

9966 [12]

<span>A) indicate the general distribution of electrons among bonded atoms in molecular compounds
B)</span>useful in naming compounds, writing formulas, and balancing chemical equations
<span>may be used to determine the simplest chemical formula </span>

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3 years ago

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Anastaziya [24]

Answer:

Science is changing because little by little scientists descover new things.

Explanation:

Discovery

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