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Marizza181 [45]
2 years ago
5

A street light is mounted at the top of a 15-ft-tall pole. A man 6 ft tall walks away from the pole with a speed of 4 ft/s along

a straight path. How fast is the tip of his shadow moving when he is 35 ft from the pole?
Physics
1 answer:
babymother [125]2 years ago
6 0

Answer:

Explanation:

height of pole = 15 ft

height of man = 6 ft

Let the length of shadow is y .

According to the diagram

Let at any time the distance of man is x.

The two triangles are similar

\frac{y-x}{y}=\frac{6}{15}

15 y - 15 x = 6 y

9 y = 15 x

y=\frac{5}{3}x

Differentiate with respect to time.

\frac{dy}{dt}=\frac{5}{3}\frac{dx}{dt}

As given, dx/dt = 4 ft/s

\frac{dy}{dt}=\frac{5}{3}\times 4

\frac{dy}{dt}=\frac{20}{3} ft/s

You might be interested in
an input force of 50 Newtons is applied through a distance of 10 meters to machine with mechanical advantage of 3. If the work o
gladu [14]
The output of the machine is

                                      (output work) =  (output force) x (distance)

                                        450 N-m      =  (output force) x (3 meters)

Divide each side
by  3 meters:                Output force = (450 N-m) / (3 m)

                                                           =    150 newtons .

With all the information given about the output work, we don't need
to know anything about the input work, or even the fact that we're
dealing with a machine.

It's comforting, though, to look back and notice that the output work
(450 N-m) is not more than the input work (500 N-m).  So everything
is nice and hunky-dory.
___________________________________

Well, my goodness !
I didn't even need to go through all of that.

Given:

-- The input force to the machine is 50 newtons.

-- The mechanical advantage of the machine is 3 .

That right there tells us that

-- The output force of the machine is 150 newtons.

We don't need any of the other given information.
5 0
2 years ago
Cori uses 475 J of energy from her muscles to push a bar 1 m on a weight machine at the gym. Between the bar’s motion , the heat
dimulka [17.4K]

Answer:

475

Explanation:

Cori does not exert any more force than 475 J, so 475 is the answer.

5 0
2 years ago
Read 2 more answers
4. Going back to the dog whistle in question 1, what is the minimum riding speed needed to be able to hear the whistle? Remember
jeyben [28]

Answer:

The minimum riding speed relative to the whistle (stationary) to be able to hear the sound at 21.0 kHz frequency is 15.7  m/s

Explanation:

The Doppler shift equation is given as follows;

f' = \dfrac{v - v_o}{v + v_s} \times f

Where:

f' = Required observed frequency = 20.0 kHz

f = Real frequency = 21.0 kHz

v = Sound wave velocity = 330 m/s

v_o = Observer velocity = X m/s

v_s = Source velocity = 0 m/s (Assuming the source is stationary)

Which gives;

20 = \dfrac{330- v_o}{330+0} \times 21

330 - v_o = (20/21)*330

v_o = 330 - (20/21)*330 = 15.7 m/s

The minimum riding speed relative to the whistle (stationary) to be able to hear the sound at 21.0 kHz frequency = 15.7  m/s.

8 0
2 years ago
The chart shows the voltage of four electric currents.
Scorpion4ik [409]

Answer:

Current X has a lower potential difference than Current Y.

Explanation:

The table is as follows:

Current Volts (V)

W     9.0

X      1.5

Y      3.0

Z      4.5

There are two quantities represented in the table:

1) Current: the current is the rate of flow of electric charge in a circuit. It is given by

I=\frac{q}{t}

where q is the amount of charge that passes a given point of a circuit in a time t. It is measured in Ampere (A).

2) Potential difference: the potential difference is the difference in electric potential between two points of a circuit. The potential difference is responsible for "pushing" the electrons through the circuit and producing a current. It is measured in Volts (V).

From the table, we see that

Current X has a lower potential difference (1.5 Volts) than Current Y (3.0 Volts)

So the correct choice is

Current X has a lower potential difference than Current Y.

3 0
2 years ago
Read 2 more answers
(a) Triply charged uranium-235 and uranium-238 ions are being separated in a mass spectrometer. (The much rarer uranium-235 is u
stiv31 [10]

Answer:

(a) 2.5 cm

(b) Yes

Solution:

As per the question:

Mass of Uranium-235 ion, m = 3.95\times 10^{- 25}\ kg

Mass of Uranium- 238, m' = 3.90\times 10^{- 25}\ kg

Velocity, v = 3.00\times 10^{5}\ m/s

Magnetic field, B = 0.250 T

q = 3e

Now,

To calculate the path separation while traversing a semi-circle:

\Delta x = 2(R_{U_{35}} - 2R_{U_{38}})

The radius of the ion in a magnetic field is given by:

R = \frac{mv}{qB}

\Delta x = 2(R_{U_{35}} - 2R_{U_{38}})

\Delta x = 2(\frac{mv}{qB} - \frac{m'v}{qB})

\Delta x = 2(\frac{m - m'}{qB}v)

Now,

By putting suitable values in the above eqn:

\Delta x = 2(\frac{3.95\times 10^{- 25} - 3.90\times 10^{- 25}}{3\times 1.6\times 10^{- 19}\times 0.250}\times 3.00\times 10^{5}) = 2.5\ cm

\Delta x = 1.25\ cm

(b) Since the order of the distance is in cm, thus clearly this distance is sufficiently large enough in practical for the separation of the two uranium isotopes.

3 0
2 years ago
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