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zzz [600]
2 years ago
6

A motorboat embarks on a trip, heading downstream in a river in which the current flows at a rate of 1.5m/s. After 30.0 minutes,

the boat has traveled a distance of 24.3 km downstream. How long will it take the boat to travel upstream to its original point of embarkation
Physics
1 answer:
Natali5045456 [20]2 years ago
3 0

Answer:

t=2413s

Explanation:

From the question we are told that:

Velocity v=1.5m/s

Time t=30min=>30*60=>1800

Distance d=24.3km

Generally the Newton's equation for Speed going down the stream is mathematically given by

 v + u = \frac{d}{t}

 1.5+v=frac{24300}{1800}

 v=12m/s

Therefore

 v + u = \frac{d}{t}

 t=\frac{24300}{12-1.5}

 t=2413s

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In case A below, a 1 kg solid sphere is released from rest at point S. It rolls without slipping down the ramp shown, and is lau
mestny [16]

Answer:

the block reaches higher than the sphere

\frac{y_{sphere}} {y_block} = 5/7

Explanation:

We are going to solve this interesting problem

A) in this case a sphere rolls on the ramp, let's find the speed of the center of mass at the exit of the ramp

Let's use the concept of conservation of energy

starting point. At the top of the ramp

         Em₀ = U = m g y₁

final point. At the exit of the ramp

         Em_f = K + U = ½ m v² + ½ I w² + m g y₂

notice that we include the translational and rotational energy, we assume that the height of the exit ramp is y₂

energy is conserved

          Em₀ = Em_f

         m g y₁ = ½ m v² + ½ I w² + m g y₂

angular and linear velocity are related

        v = w r

the moment of inertia of a sphere is

         I = \frac{2}{5} m r²

we substitute

         m g (y₁ - y₂) = ½ m v² + ½ (\frac{2}{5} m r²) (\frac{v}{r})²

         m g h = ½ m v² (1 + \frac{2}{5})

where h is the difference in height between the two sides of the ramp

h = y₂ -y₁

         mg h = \frac{7}{5} (\frac{1}{2} m v²)

         v = √5/7  √2gh

This is the exit velocity of the vertical movement of the sphere

         v_sphere = 0.845 √2gh

B) is the same case, but for a box without friction

   starting point

          Em₀ = U = mg y₁

   final point

          Em_f = K + U = ½ m v² + m g y₂

          Em₀ = Em_f

          mg y₁ = ½ m v² + m g y₂

          m g (y₁ -y₂) = ½ m v²

          v = √2gh

this is the speed of the box

          v_box = √2gh

to know which body reaches higher in the air we can use the kinematic relations

          v² = v₀² - 2 g y

at the highest point v = 0

           y = vo₀²/ 2g

for the sphere

           y_sphere = 5/7 2gh / 2g

           y_esfera = 5/7 h

for the block

           y_block = 2gh / 2g

            y_block = h

       

therefore the block reaches higher than the sphere

         \frac{y_{sphere}} {y_bolck} = 5/7

3 0
3 years ago
Select the correct answer.<br> Which type of energy is thermal energy a form of
elena-s [515]
Kinetic energy. thermal energy (a low form of energy ) is a form of kinetic energy as it is produced as a result of motion of particles either if they vibrate at their position or they move along longer paths. Motion produces friction or resistance which leads to excitation and thus the heat is produced. The higher the motion of the particles, the higher would be the thermal energy.
7 0
2 years ago
The efficiency of a light source is the percentage of its energy input that gets radiated as visible light. if some of the blue
Anestetic [448]

The efficiency of a light source is the percentage of its energy input that gets radiated as visible light if some of the blue light in an led is used to cause a fluorescent material to glow the overall efficiency of the LED decreases.

How efficient is LED?

Different wavelengths that correlate to different visible colours are used in LED light therapy. Various shades pierce the skin at different rates.

  1. Your skin's outermost layer is impacted by blue light.
  2. Yellow light is more enveloping.
  3. Red light penetrates your skin more deeply.
  4. The deepest penetrating light is near-infrared.

Different LED hues have various effects. For instance, according to experts red LED light therapy has the potential to reduce inflammation and boost collagen formation, which declines with age and is crucial for maintaining youthful-looking skin.

Acne-causing bacteria may be destroyed by a blue LED light therapy (P. acnes).

Hence the answer is the overall efficiency of the LED decreases.

Learn more about wavelength here,

brainly.com/question/1263539

# SPJ4

7 0
2 years ago
What is the answer to this?
jeka57 [31]

Answer:

I think it is the forth one

7 0
2 years ago
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What were some benefits to the american television from analog broadcast to digital broadcast?
Elanso [62]

Answer:

nothing no no no

Explanation:

nothing cause no

8 0
2 years ago
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