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Airida [17]
3 years ago
9

A boat travels upstream for 12 miles in 3 hours and returns in 2 hours traveling downstream in a river. What is the rate of the

boat in still water and the rate of the current?
Physics
1 answer:
kaheart [24]3 years ago
7 0

Answer:

Rate of boat in still water = 5mile/hour

Rate of the current= 1 mile/hr

Explanation:

The boat is moving upstream at the rate= 12miles/3hours= 4mph

The boat is moving downstream at the rate = 12miles/2hours = 6mph

Let y be the speed of boat

And C the current of water

Y + C = 6 ...eq1

Y - C = 4 ...eq2

Adding eq1 and eq2

2Y = 10

Y= 10/2 = 5

Y= 5mph

Put Y = 5 in eq2

5 + C = 6

C = 6 - 5

C= 1 mph

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During metamorphism, what is the major effect of chemically active fluids?
xz_007 [3.2K]

Answer:

Option b

Explanation:

Metamorphism is the process where the variation of the geological texture resulting from the different arrangement of the minerals or the variation of minerals in protoliths, i.e., pre- existing rocks take place such that there occurs no change in state of the protolith, i.e., it does not melt into magma.

The change takes place as a result of the presence of chemically active fluids, heat and pressure.

There is a reaction between the chemically active fluid and the rock through which it passes and promotes the movement of the dissolved ions of silicate and promotes the growth of the mineral grains.

7 0
3 years ago
A trained eye in the dark for an extended period of time may pick up a light stimulus from a light source, at the lowest radiate
frez [133]

Answer:

    #_photons = 30 photons / s

Explanation:

Let's start by finding the energy of a photon of light, let's use the Planck relation

         E = h f

the speed of light is related to wavelength and frequency

         c = λ f

we substitute

         E = h c /λ

         E₀ = 6.63 10⁻³⁴ 3 10⁸/500 10⁻⁹

         E₀ = 3.978 10⁻¹⁹ J

now let's use a direct proportion rule. If the energy of a photon is Eo, how many fornes has an energy E = 1.2 10⁻¹⁷ J in a second

          #_photons = 1 photon   (E / Eo)

          #_photons = 1  1.2 10⁻¹⁷ /3.978 10⁻¹⁹

          #_photons = 3.0 10¹

          #_photons = 30 photons / s

3 0
2 years ago
A car starts from rest and accelerates uniformly for a five seconds along a straight road. If speed obtained by the car is 72 km
Step2247 [10]

Answer:

50 meters

Explanation:

Let's start by converting to m/s. There are 3600 seconds in an hour and 1000 meters in a kilometer, meaning that 72km/h is 20m/s.

v_f=v_o+at

Since the car starts at rest, you can write the following equation:

20=0+a(5) \\\\a=20\div 5=4 m/s^2

Now that you have the acceleration, you can do this:

d=v_o+\dfrac{1}{2}at^2

Once again, there is no initial velocity:

d=\dfrac{1}{2}(4)(5)^2=2 \cdot 25=50m

Hope this helps!

8 0
3 years ago
An airplane dropped a flare from a height of 2860 feet above a lake. How many seconds did it take for the flare to reach the wat
KATRIN_1 [288]

Answer: 13.2 seconds.

Explanation: using equation of motion; S= ut +1/2at² where u = initial velocity=0

S= distance travelled

a = acceleration due gravity

t= time.

1 foot = 0.305m so,

S= 2860 feet =872.3m

S= ut+1/2 at²

872.3 = 0×t + 1/2×10 × t²

872.3 =0 + 5t²

T²= 872.3/5

T²= 174.46

Take the square root of T we then have;

t = 13.2 seconds to one decimal place.

8 0
3 years ago
Read 2 more answers
A uniform rod of length L, mass M, is suspended by two thin strings. Which of the following statements is true
Fantom [35]

Answer:

(d) not enough info

Explanation:

because it doesn't specify where the strings are attached

if it was the two ends of the rod then T1 would be equal to T2

6 0
3 years ago
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