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3 years ago

Motion equation of object is

Physics

1 answer:

Ganezh [65]3 years ago

5 0

Take the derivative to find the velocity of the object:

$v=\dfrac{\mathrm dx}{\mathrm dt}=-12+6t$

The object stops when $v=0$ :

$-12+6t=0\implies6t=12\implies t=2$

so the answer is E.

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The pressure drop needed to force water through a horizontal 1-in diameter pipe if 0.60 psi for every 12-ft length of pipe. Dete

oksian1 [2.3K]

Answer:

The shear stress at a distance 0.3-in away from the pipe wall is 0.06012lb/ft²

The shear stress at a distance 0.5-in away from the pipe wall is 0

Explanation:

Given;

pressure drop per unit length of pipe = 0.6 psi/ft

length of the pipe = 12 feet

diameter of the pipe = 1 -in

Pressure drop per unit length in a circular pipe is given as;

$\frac{\delta P}{L} = \frac{2 \tau}{r} \\\\$

make shear stress (τ) the subject of the formula

$\frac{\delta P}{L} = \frac{2 \tau}{r} \\\\\tau = \frac{\delta P *r}{2L}$

Where;

τ is the shear stress on the pipe wall.

ΔP is the pressure drop

L is the length of the pipe

r is the distance from the pipe wall

Part (a) shear stress at a distance of 0.3-in away from the pipe wall

Radius of the pipe = 0.5 -in

r = 0.5 - 0.3 = 0.2-in = 0.0167 ft

ΔP = 0.6 psi/ft

ΔP, in lb/ft² = 0.6 x 144 = 86.4 lb/ft²

$\tau = \frac{\delta P *r}{2L} = \frac{86.4 *0.0167}{2*12} =0.06012 \ lb/ft^2$

Part (b) shear stress at a distance of 0.5-in away from the pipe wall

r = 0.5 - 0.5 = 0

$\tau = \frac{\delta P *r}{2L} = \frac{86.4 *0}{2*12} =0$

3 0

3 years ago

What must the diver's minimum speed be just as she leaves the top of the cliff so that she will miss the ledge at the bottom, wh

Dafna1 [17]

Answer:

1.08 m/s

Explanation:

This can be solved with two steps, first we need to find the time taken to fall 9.5 m, then we can divide the horizontal distance covered with time taken to calculate the velocity.

Time taken to fall 9.5 m

vertical acceleration = a = 9.8 m/s^2.

vertical velocity = 0, (since there is only horizontal component for velocity, )

distance traveled s = 9.5 m.

Substituting these values in the equation

$s= u \timest+0.5at^{2}$

$t= \sqrt{\frac{2s}{g} }$

$t=\sqrt{\frac{2\times9.5}{9.8} }$

⇒ t= 1.392 sec

Velocity needed

We know the time taken (1.392 s) to travel 1.5 m,

So velocity = 1.5 m / 1.392 s = 1.08 m/s

hence velocity of the diver must be at least 1.08 m/s

4 0

3 years ago

Use the following photoelectric graph to answer the following question:

klio [65]

The photoelectric effect is obtained when you shine a light on a material, resulting in the emission of electrons.

The kinetic energy of the electrons depends on the frequency of the light:
K = h(f - f₀)

where:
K = kinetic energy
h = Planck constant
f = light frequency
f₀ = threshold frequency

Rearranging the formula in the form y = m·x + b, we get:
K = hf - hf₀
where:
K = dependent variable
f = indipendent variable
h = slope
hf₀ = y-intercept

Every material has its own threshold frequency, therefore, what stays constant for all the materials is h = Planck constant (see picture attached).

Hence, the correct answer is C) the slope.

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3 years ago

The city bus traveled 30 miles in 30 minutes. What was its speed in mph?

jonny [76]

The answer will be B.60mph

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3 years ago

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Investigate the relationship between volume and pressure of a gas at a constant temperature.

sveta [45]

Gay Lussac's Law states: At a constant volume Pressure divided by Temperature isconstant P/T = k Together these three laws form the foundation of the Ideal GasLaw. Objective: Students will investigate Gay Lussac's Law relating pressure andtemperature at a constant temperature.

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3 years ago