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3 years ago

A Long Jumber leaves the ground at on

Physics

1 answer:

MArishka [77]3 years ago

7 0

Answer:

horizontal velocity vh = 6*cos(30°) = 6*(√3)/2 = 3√3 m/s

initial vertical velocity vv = 6*sin(30°) = 6/2 = 3m/s

Using s = ut + at2/2 for change in vertical distance in time t, with acceleration a (-9.8m/s2) and initial velocity u (vv = 3m/s) we have

0 = 3*t - 9.8*t2/2 or t = 6/9.8 s (ignoring the t = 0 solution, which just represents staying still!).

The horizontal distance in time t is vh*t or 3√3*6/9.8 m

Explanation:

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Is it true or false that on the Celsius temperature scale, there are no negative numbers? If false, why?

jeka57 [31]

The Celsius Temperature scale has negative values, anything lower than 32 Fahrenheit/0° is negative, for reference using the celsius scale water freezes at 0° and boils at 100°, hope this helps!

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4 years ago

A body is thrown vertically upwards.Its velocity keeps on decreasing. What happens to its kinetic energy when it reaches the max

Nikolay [14]

The kinetic energy will rise once the body comes back down. As it goes up, the potential energy increases while the kinetic energy decreases. Once the body is at its maximum height, the potential energy is at it’s highest. When it starts falling, it will gain kinetic energy and lose potential energy.

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4 years ago

Read 2 more answers

sineoko [7]

Answer:

a) λ = 5,084 10⁻⁷ m , b) P = 3.63 10²⁶ W , c) P = 5.8 10²⁷ W and d) λ = 2.54 10⁻⁷ m

Explanation:

a) The maximum emission of the sun can be calculated using the Win equation

λ T = 2,898 10⁻³ m.K

λ = 2,898 10⁻³ / T

λ = 2,898 10⁻³ / 5700

λ = 5,084 10⁻⁷ m

λ = 5,084 10⁻⁷ m (1 10⁹ nm / 1m) =

λ = 5,084 10² nm = 508.4 nm

photon in the visible range

b) The emission of the Sun, is described by the Stefan equation

P = σ A e T⁴

Where σ is the Stefan-Boltzmann constant that vslue is 5,670 10-8 W/m²K⁴, A area of the Sun, and e the emissivity that for a perfect black body is 1

In order to use this equation, we must calculate the area of the sun, we consider it a perfect sphere

r = 695,000 km (1000m / 1 km) = 6.95 10⁸ m

Area of a sphere

A = 4π R²

A = 4π (6.95 10⁸8)²

A = 6.07 10¹⁸ m²

P = 5,670 10⁻⁸ 6.07 10¹⁸ 1 5700⁴

P = 3.63 10²⁶ W

c) The new temperature is double the previous one

T = 2 To

Let's substitute in the formula and calculate

P = σ A e (2To)⁴

P = σ A e T⁴ 2⁴

Po = σ A e T4 = 3.63 10 26 W

P = 16 Po

P= 16 (3.63 10²⁶)

P = 5.8 10²⁷ W

d) Let's calculate the explicit value of the temperature and use the Win equation

T = 2 5700

T = 11400K

λ = 2,898 10⁻³ / 11400

λ = 2.54 10⁻⁷ m

λ = 2.54 10²nm = 254 nm

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3 years ago

A cylinder of mass mm is free to slide in a vertical tube. The kinetic friction force between the cylinder and the walls of the

Zinaida [17]

Answer:

$y = \frac{-f +/- \sqrt{f^{2} +2kmg}}{k}$

Explanation:

Let y₀ be the initial position of the cylinder when the spring is attached and y its position when it is momentarily at rest.From work-kinetic energy principles, The work done by the spring force + work done by friction + work done by gravity = kinetic energy change of the cylinder

work done by the spring force = ¹/₂k(y₀² - y²)

work done by friction = - f(y - y₀)

work done by gravity = mg(y - y₀)

kinetic energy change of the cylinder = ¹/₂m(v₁² - v₀²)

So ¹/₂k(y₀² - y²) - f(y - y₀) + mg(y - y₀) = ¹/₂m(v₁² - v₀²)

Since the cylinder starts at rest, v₀ = 0. Also, when it is momentarily at rest, v₁ = 0

¹/₂k(y₀² - y²) - f(y - y₀) + mg(y - y₀) = ¹/₂m(0² - 0²)

¹/₂k(y₀² - y²) - f(y - y₀) + mg(y - y₀) = 0

¹/₂ky₀² + fy₀ - mgy₀ -¹/₂ky² - fy + mgy = 0

¹/₂ky₀² + fy₀ - mgy₀ = ¹/₂ky² + fy - mgy

Let y₀ = 0, then the left hand side of the equation equals zero. So,

0 = ¹/₂ky² + fy - mgy

¹/₂ky² + fy - mgy = 0

Using the quadratic formula

$y = \frac{-f +/- \sqrt{f^{2} - 4 X\frac{k}{2} X -mg}}{2 X \frac{k}{2} }\\ y = \frac{-f +/- \sqrt{f^{2} +2kmg}}{k}$

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3 years ago

Which of the following should maintain the appropriate temperature and humidity levels and provide closed-loop recirculating: a.

Diano4ka-milaya [45]

If we define each of the systems that are given in the options we will have to:

Air conditioning is the air treatment that modifies its conditions to suit certain needs, i.e., the process of removing heat and moisture from the interior of an occupied space to improve the comfort of occupants. Air conditioners are also responsible for controlling humidity in closed rooms.

Positive Pressurization is a pressure within a system that is greater than the surrounding environment. Consequently, if there is any leakage of the system with positive pressure, it will leave the surrounding environment. There is no temperature or humidity control here

Ventilation is done by artificially creating depressions or overpressures in air distribution ducts or building areas. The fans are mechanically responsible for increasing the volume flow of air in a system. Moisture is not controlled directly.

Therefore the correct answer is A.

4 0

4 years ago