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Rom4ik [11]
3 years ago
9

A rock is thrown down with an initial speed of 25.3 m/s from a bridge to the water below. It takes 2.29 s for the rock to hit th

e water. How high is the bridge above the water in meters?
Physics
1 answer:
Rzqust [24]3 years ago
7 0
<h2>Height of bridge is 83.66 m</h2>

Explanation:

We have equation of motion s = ut + 0.5 at²

        Initial velocity, u = 25.3 m/s

        Acceleration, a = 9.81 m/s²  

        Time, t = 2.29 s      

     Substituting

                      s = ut + 0.5 at²

                      s = 25.3 x 2.29 + 0.5 x 9.81 x 2.29²

                      s = 83.66 m

      Height of bridge is 83.66 m

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How heat is conducted along a metal bar?
nikdorinn [45]

Answer:

If one end of a metal bar is heated, the atoms at that end vibrate more than the atoms at the cold end. The vibration spreads along the bar from atom to atom.

Explanation:

The spread of heat in this way is called conduction. Metals are good conductors of heat.

3 0
3 years ago
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Helium-oxygen mixtures are used by divers to avoid the bends and are used in medicine to treat some respiratory ailments. What p
Temka [501]

Answer:

The percentage by mole of Helium present in the Helium-Oxygen mixture is = 66.6%

Explanation:

From General gas equation.

PV = nRT...............................  Equation 1

Where n = number of moles, V = volume, P = pressure, T = temperature, P = pressure, V = volume.

n = mass/molar mass .................. Equation 2

substituting equation 2 into equation 1.

PV = (mass/molar mass)RT

⇒ Mass/molar mass = PV/RT..................... Equation 3

But mass = Density × Volume

⇒ M = D × V.................... Equation 4

Where D = density, M = mass

Substituting equation 4 into equation 3

DV/molar mass = PV/RT............ Equation 5

Dividing both side of the equation by Volume (V) in Equation 5

D/molar mass = P/RT .............. Equation 6

Cross multiplying equation 6

D × RT = P × molar mass

∴ Molar mass = (D × RT)/P.................. Equation 7

Where D = 0.518 g/L , R = 0.0821 atm dm³/K.mol,

T = 25°C = 25 + 273 = 298 K,

P =721 mmHg = (721/760) atm= 0.949 atm

Substituting these values into equation 7

Molar mass = (0.518 × 0.0821 × 298)/0.949

Molar mass = 13.35 g/mole

The molar mass of the mixture is =13.35 g/mole

Let y be the mole fraction of Helium and 1-y be the mole fraction of oxygen.

∴ 13.35 = 4(y) + 32(1-y)

13.35 = 4y + 32 - 32y

Collecting like terms in the equation,

32y - 4y = 32 - 13.35

28y = 18.65

y = 18.65/28

y =0.666

y = 0.666 × 100 = 66.6%

∴The percentage by mole of Helium present in the Helium-Oxygen mixture is = 66.6%

6 0
3 years ago
A small ball is attached to the lower end of a 0.800-m-long string, and the other end of the string is tied to a horizontal rod.
mestny [16]

Answer:

a = 17.68 m/s²

Explanation:

given,

length of the string, L = 0.8 m

angle made with vertical, θ = 61°

time to complete 1 rev, t = 1.25 s

radial acceleration = ?

first we have to calculate the radius of the circle

 R = L sin θ

 R = 0.8 x sin 61°

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now, calculating at the angular velocity

\omega =\dfrac{2\pi}{T}

\omega =\dfrac{2\pi}{1.25}

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now, radial acceleration

 a = r ω²

 a = 0.7 x 5.026²

a = 17.68 m/s²

hence, the radial acceleration of the ball is equal to 17.68 rad/s²

7 0
3 years ago
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fiasKO [112]
The formula for velocity vf = vi + at

First list your given information

2m/s Is your initial velocity (vi)
6m/s is you final velocity (vf)
2 seconds is your time (t)

Since you want the a for acceleration get a by itself

a = (vf-vi)/t

So a= (6-2)/2

a= 4/2

a=2

Now units

the units for acceleration are m/sx^{2}

2m/sx^{2}
7 0
3 years ago
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mote1985 [20]
If the object, ends up with a positive charge, then it is missing electrons. if it is missing electrons, then it must have been removed form the object during the rubbing process.
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