A river flows with a uniform velocity vr. A person in a motorboat travels 1.22 km upstream, at which time she passes a log floating by. Always with the same engine throttle setting, the boater continues to travel upstream for another 1.45 km, which takes her 69.1 min. She then turns the boat around and returns downstream to her starting point, which she reaches at the same time as the same log does. How much time does the boater spend traveling back downstream

Answers

Answer 1

Answer:

 t ’= [tex]\frac{1450}{0.6499 + 2 v_r}[/tex],  v_r = 1 m/s       t ’= 547.19 s

Explanation:

This is a relative velocity exercise in a dimesion, since the river and the boat are going in the same direction.

By the time the boat goes up the river

        v_b - v_r = d / t

By the time the boat goes down the river

        v_b + v_r = d '/ t'

let's subtract the equations

       2 v_r = d ’/ t’ - d / t

       d ’/ t’ = 2v_r + d / t

       [tex]t' = \frac{d'}{ \frac{d}{t}+ 2 v_r }[/tex]

In the exercise they tell us

         d = 1.22 +1.45 = 2.67 km= 2.67 10³ m

         d ’= 1.45 km= 1.45 1.³ m

at time t = 69.1 min (60 s / 1min) = 4146 s

the speed of river is v_r

      t ’= [tex]\frac{1.45 \ 10^3}{ \frac{ 2670}{4146} \ + 2 \ v_r}[/tex]

      t ’= [tex]\frac{1450}{0.6499 + 2 v_r}[/tex]

In order to complete the calculation, we must assume a river speed

          v_r = 1 m / s

       

let's calculate

      t ’= [tex]\frac{ 1450}{ 0.6499 + 2 \ 1}[/tex]

      t ’= 547.19 s


Related Questions

One reason why it’s often easy to miss an action-reaction pair is because of the ________ of one of the objects.

Answers

Answer:

an action-reaction pair is because one of the objects is often much more massive and appears to remain motionless when a force acts on it. It has so much inertia, or tendency to remain at rest, that it hardly

A particle with a charge of -4.3 μC and a mass of 4.4 x 10-6 kg is released from rest at point A and accelerates toward point B, arriving there with a speed of 80 m/s. The only force acting on the particle is the electric force. What is the potential difference VB - VA between A and B? If VB is greater than VA, then give the answer as a positive number. If VB is less than VA, then give the answer as a negative number.

Answers

Answer:

ΔV = - 3274 V

Explanation:

For this exercise we can use conservation of energy

starting point.

         Em₀ = U = q ΔV

final point

          Em_f = K = ½ m v²

energy is conserved

          Em₀ = Em_f

          q ΔV = ½ m v²

          ΔV = [tex]\frac{m \ v^2 }{q}[/tex]

let's calculate

          ΔV = [tex]\frac{4.4 \ 10^{-6} \ 80^2 }{ 2 \ 4.3 10^{-6} }[/tex]

          ΔV = 3274.4 1 V

since the charge q is negative, the potential at point B must be less than the potential at point A, so the answers

          ΔV = - 3274 V

Connective Tissue in a tendon is

Answers


Overview. A tendon is a fibrous connective tissue which attaches muscle to bone. Tendons may also attach muscles to structures such as the eyeball. A tendon serves to move the bone or structure.

At what speed, in m/s, would a moving clock lose 1.3ns in 1.0 day according to experimenters on the ground?

Answers

Answer:

v=0.14c

Explanation:

Two insulated wires, each 2.64 m long, are taped together to form a two-wire unit that is 2.64 m long. One wire carries a current of 7.68 A; the other carries a smaller current I in the opposite direction. The two wire unit is placed at an angle of 65.0o relative to a magnetic field whose magnitude is 0.59 T. The magnitude of the net magnetic force experienced by the two-wire unit is 4.11 N. What is the current I

Answers

Answer:

[tex]4.77\ \text{A}[/tex]

Explanation:

F = Magnetic force = 4.11 N

[tex]I_n[/tex] = Net current

[tex]I_2[/tex] = Current in one of the wires = 7.68 A

B = Magnetic field = 0.59 T

[tex]\theta[/tex] = Angle between current and magnetic field = [tex]65^{\circ}[/tex]

[tex]l[/tex] = Length of wires = 2.64 m

[tex]I[/tex] = Current in the other wire

Magnetic force is given by

[tex]F=I_nlB\sin\theta\\\Rightarrow I_n=\dfrac{F}{lB\sin\theta}\\\Rightarrow I_n=\dfrac{4.11}{2.64\times 0.59 \sin65^{\circ}}\\\Rightarrow I_n=2.91\ \text{A}[/tex]

Net current is given by

[tex]I_n=I_2-I\\\Rightarrow I=I_2-I_n\\\Rightarrow I=7.68-2.91\\\Rightarrow I=4.77\ \text{A}[/tex]

The current I is [tex]4.77\ \text{A}[/tex].

What is the mass of an object if it is moving at a speed of 10 m/s and has 400 J of kinetic energy?

Answers

Answers:

8 kg

Explanation:

Kinetic Energy = (mass × velocity × velocity) ÷ 2

We know that Kinetic Energy = 400 J and velocity = 10 m/s.

KE = (m × v × v) ÷ 2

400 J = (m × 10 m/s × 10 m/s) ÷ 2

400 J = m × 50 m^2/s^2

To find the mass you will divide 400 J and 50 m^2/s^2.

m = 8 kg

You can also check it if it gives you 400 J.

KE = (m × v × v) ÷ 2

KE = (8 kg × 10 m/s × 10 m/s) ÷ 2

KE = 400 J

So this means that the mass is 8 kg. I know that it is a bit confusing, but when you do J (joules) ÷ m^2/s^2 = kg (kilograms). Hope this helps, thank you !!

Choose the best explanation from among the following:_________.
1. Charge is conserved, and therefore the mass of the object will remain the same.
2. A positive charge increases an object's mass; a negative charge decreases its mass.
3. To give the object a negative charge we must give it more electrons, and this will increase its mass.

Answers

Answer: 3. To give the object a negative charge we must give it more electrons, and this will increase its mass.

Explanation:

Suppose we have an object and we negatively charge it.

Then we are "adding" N electrons to the object.

Remember that the mass of an electron is:

m = 9.11*10^(-31) kg

Then if we add N electrons to an object of mass M, the new mass of the object will be:

Mass = M + N*9.11*10^(-31) kg

So we will have an (almost negligible) increase of the mass of the object.

(Something similar can happen if the object is positively charged, where we remove electrons, then the mass of the object decreases)

Then the correct option is:

3. To give the object a negative charge we must give it more electrons, and this will increase its mass.

According to Coulomb's Law, if the distance between two charged particles is doubled, the electric force will be _________. *

Answers

Answer: reduced by 1/4

Explanation:

The force will be reduced by 1/4. Try plugging in 2r, then squaring it. You will get 4r^2, which is essentially dividing the force by 4

A sports car of mass m has the same kinetic energy as an SUV with a mass 3m as each is driven along the same road. Which vehicle, if either, has the larger momentum and what is the difference in their momenta, if any

Answers

Answer:

Explanation:

Kinetic energy ( KE ) = 1/2 m v²

= m²v² / 2 m = p² / 2m where p is momentum

KE = p² / 2m

p² = 2m KE

KE is constant

p is proportional to mass

So car having higher mass will have higher momentum .

p₁ = √ ( 2 m x KE )

p₂ = √ ( 6 m x KE )

p₂ - p₁ =  √ ( 6 m x KE ) - √ ( 2 m x KE )

= √KE m ( √6 - √2 )

Kinetic energy ( K.E )

[tex]= \frac{1}{2} m v^2\\\\= \frac{m^2 v^2}{2 m} \\\\= \frac{p^2}{2m}[/tex]

where p is momentum

[tex]K.E =\frac{p^2}{2m}\\\\p^2 = 2m. KE[/tex]

KE is constant

p is proportional to mass

So car having higher mass will have higher momentum .  

[tex]p_1 =\sqrt{(2m*K.E)}\\\\p_2 = \sqrt{(6m*K.E)} \\\\p_2 - p_1 = \sqrt{(6m*K.E)} -\sqrt{(2M*K.E} \\\\p_2 - p_1 = \sqrt{K.E m(\sqrt{6}-\sqrt{2}) }[/tex]

The difference is shown above.

Learn more:

brainly.com/question/20658056

What is the frequency of highly energetic ul-
traviolet radiation that has a wavelength of
124 nm?
The speed of light is 3 x 108 m/s.
Answer in units of Hz.

Answers

Frequency = (speed) / (wavelength)

Frequency = (3 x 10⁸ m/s) / (124 x 10⁻⁹ m)

Frequency = 2.42 x 10¹⁵ Hz

A car traveling 85 km/h is 250 m behind a truck
traveling 73 km/h.

Answers

Time needed = t = 20.83 s

Further explanation

Given

car speed = 85 km/h

truck speed = 73 km/h

Required

the time it takes for the car to reach the truck

Solution

When the car reaches the truck, the distance between them will be the same

x car - 250 m = x truck

General formula for distance (d) :

d = v.t

So the equation becomes :

85t-250 = 73t

12t=250

t = 20.83 s

Carousel conveyors are used for storage and order picking for small parts. The conveyorsrotate clockwise or counterclockwise, as necessary, to position storage bins at the storageand retrieval point. The conveyors are closely spaced, such that the operators travel timebetween conveyors is negligible. The conveyor rotation time for each item equals 1 minute;the time required for the operator to retrieve an item after the conveyor stops rotatingequals 0.25 minute. How many carousel conveyors can one operator tend without creatingidle time on the part of the conveyors

Answers

Answer:

the number of carousel conveyors that an operator can operate without any idle time is 5

Explanation:

Given the data in the question;

first we express the equation for number of carousel conveyors that can be operated by an operator;

n' = [tex]\frac{(a + t)}{( a + b)}[/tex]

where a is the concurrent activity time ( 0.25 minute )

b is the independent operator activity time

t is the independent machine activity time( 1 )

Now independent activity time is zero as the operator is not performing any inspection or packaging tasks.

So time taken for the operator to retrieve the finished item at the end of the process is the concurrent activity and independent machine activity time, the conveyor rotation time of each item

so

we substitute

0.25min for a, 1 for t and 0min for b

n' = [tex]\frac{(0.25min + 1min)}{( 0.25min+ 0 min)}[/tex]

n' = 1.25 min / 0.25

n' - 5

Therefore, the number of carousel conveyors that an operator can operate without any idle time is 5

The "problem of perception" is best characterized as?

Answers

Answer:

making sense of a 3-d world from 2-d data

Explanation:

Jshshshsshhsbxbxbxbxbdbdbd

A baseball player hits a 0.15 kg 0.15kg0, point, 15, start text, k, g, end text baseball that is initially at rest, changing its momentum by 11 kg ⋅ m s 11 s kg⋅m ​ 11, start fraction, start text, k, g, end text, dot, start text, m, end text, divided by, start text, s, end text, end fraction.

Answers

Answer:

73.3m/s

Explanation:

We can find the velocity of the player.

Momentum = mass * velocity

Given

Mass = 0.15kg

Momentum = 11kgm/s

Get the velocity

Velocity = Momentum/Mass

Velocity = 11/0.15

Velocity = 73.3m/s

Hence the velocity of the player is 73.3m/s

A 20-turn coil of area 0.32 m2 is placed in a uniform magnetic field of 0.055 T so that the perpendicular to the plane of the coil makes an angle of 30∘ with respect to the magnetic field.

The flux through the coil is

Answers

Answer:

1.5 * 10^-2 Tm^2

Explanation:

Electric Flux = B.A cos(theta)

B = 0.055 T

A = 0.32 m^2

theta = 30

Electric Flux = (0.055 T).(0.32 m^2).Cos(30) = 0.0152 = 1.5 * 10^-2 Tm^2

Fred's lightbulb is 45% efficient, and Fran's is 75% efficient. If they both use the same amount of electric energy, which produces more light energy? ​

Answers

Answer:

Frank's 75% efficient light bulb will shine brighter.

Explanation:

The brightness of a bulb is gotten from the power equation;

P = I²R

The more the power rating in watts, the more the brightness.

Now, if they both use the same amount of energy but yet have different efficiency, it means we will just multiply the efficiency by the power.

Thus, 75% efficiency will yield more power than a 45% efficient one.

Therefore, Frank's light bulb will shine brighter.

During a phase change the temperature of a substance remains constant this is because during a phase heat changes the ____ energy of particles in a substance without changing their ____ energy

Answers

Answer:

Explanation:

individual and then net

hope that helps I could be wrong about this one though

pls help ;-; this is the question btw

Answers

The answer is "Infrared"

Hope this helps

Answer:

x-rays

Explanation:

A truck travels on a straight road at a velocity of 17 meters per second. Over 20

seconds, it accelerates uniformly to 27 meters per second. What distance did the truck

travel during this acceleration?

Answers

Answer:

Distance, S = 440 meters.

Explanation:

Given the following data;

Initial velocity, u = 17m/s

Time, t = 20 seconds

Final velocity, v = 27m/s

To find the distance;

First of all, we would determine the acceleration of the truck.

Acceleration = (v-u)/t

Substituting the given values into the equation, we have;

Acceleration = (27 - 17)/20

Acceleration = 10/20

Acceleration = 0.5m/s²

Now, we would use the second equation of motion to find the distance traveled.

S = ut + ½at²

S = 17*20 + ½*0.5*20²

S = 340 + 0.25*400

S = 340 + 100

S = 440m

The equations of motion can be used to obtain the distance covered as 440 m.

We have to use of the equations that are used for uniformly accelerated motion in solving the problem. The chosen equation must be;

v^2 = u^2 + 2as and v = u + at

v = final velocity

u = initial velocity

a = acceleration

s = distance

To obtain the acceleration;

27 = 17 + 20(a)

27 - 17 = 20a

a = 0.5 ms-2

Now, to obtain the distance;

v^2 = u^2 + 2as

v^2 - u^2/as = s

s = (27)^2 - (17)^2/2(0.5)

s = 440 m

Learn more about the acceleration: https://brainly.com/question/12134554

What is the maximum height achieved if a 0.400 kg mass is thrown straight upward with an initial speed of 40.0 m⋅s−1? Ignore the effect of air resistance

Answers

The maximum height : 81.63 m

Further explanation

Given

0.4 kg mass

vo = initial speed = 40 m/s

Required

the maximum height

Solution

We can use the law of conservation energy(ME=PE+KE) or use parabolic motion

For parabolic motion :

h max = (vo²sin²θ)/2g

θ = 90°(straight upward)

Input the value :

h max = (40²sin²90°)/2 x 9.8

h max = 81.63 m

From the center of the Earth to the moon, what should the orbital radius of such satellite be in order to stay over the same point on the earth’s surface?​

Answers

In order to have a period that matches the Earth's rotation, a satellite must be in a circular orbit, and 42,164 km from the center of the Earth.

But that's not quite enough to make sure that it always stays over the same point on the Earth's surface (and appears motionless in the sky). For that to happen, the satellite's orbit has to be directly over the Equator.

The Moon has nothing to do with any of this.

Using the graph, when (in seconds) would you expect the object to have the highest velocity? Explain your answer.

Answers

Answer:

blue

Explanation:

nswer the following about two objects, A and B, whose motion produced ihe following ... "A" starts with a greater (t) position. Since they ... since you are moving away from the origin

what do you call these sound waves whose frequency is above 20000 hertz

Answers

Answer:

Untrasound

Explanation:

Your welcome :)

What fitness component is plank exercises?

Answers

Answer:

The plank (also called a front hold, hover, or abdominal bridge) is an isometric core strength exercise that involves maintaining a position similar to a push-up for the maximum possible time.

Explanation:

please mark me has brainllest

a ball is thrown upward with a beginning speed of 40m/s. The graph below shows how the speed of the ball changes until it reaches its maximum height.

use the graph to find
a) the time when the ball reaches its maximum height
b) the acceleration of the ball
c) the maximum height the ball went​

Answers

Answer:

a) 4.0816s

b) -9.8 ms^-1

c) 81.63265m

A car traveling 85 km/h is 250 m behind a truck
traveling 73 km/h.

Answers

Time needed = t = 20.83 s

Further explanation

Given

car speed = 85 km/h

truck speed = 73 km/h

Required

the time it takes for the car to reach the truck

Solution

When the car reaches the truck, the distance between them will be the same

x car - 250 m = x truck

General formula for distance (d) :

d = v.t

So the equation becomes :

85t-250 = 73t

12t=250

t = 20.83 s


A boy throws a rock with an initial horizontal velocity of 17.0 m/s and an initial vertical velocity of 21.0 m/s. How high above the boy's hand is the rock after 2.8 s?

Answers

Answer:

53.2

Explanation:

You can use the kinematic equation: displacement of x = (initial velocity + final velocity)*t/2

Subsititing: 17+21 = 38 * 2.8/2 = 53.2

Note: Displacement = distance between the 2 points

What is moral duty?Please tell me the answer of this question. ​

Answers

Explanation:

Moral duties are the duties performed by the people on the basis of humanity and moral values. The following are some of the moral duties :

Respecting elders and loving juniorsHelped the needy , poor and helpless peopleHaving friendly behavior with othersRespecting everyone as human beingBeing obedient and respectful to parents , elderly people and teachers.Living ideal and respectful life

Hope I helped ! ♡

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A train 350 m long is moving on a straight track with a speed of 84.1 km/h. The engineer applies the brakes at a crossing, and later the last car passes the crossing with a speed of 15.8 km/h. Assuming constant acceleration, determine how long the train blocked the crossing. Disregard the width of the crossing.

Answers

Answer:

t = 25.0 s

Explanation:

Assuming that the engineer applies the brakes just over the crossing, the train moves exactly 350 m at a constant acceleration, with a final speed (when the last car of the train leaves the crossing) of 15.8km/h.Since we know the initial and final speeds, and the horizontal distance traveled (the length of the train) we can use the following kinematic equation to get the acceleration:

       [tex]v_{f}^{2} - v_{o}^{2} = 2*a* \Delta x (1)[/tex]

Since we need to find the time in seconds, it is advisable to convert vf and  vo to m/s first, as follows:

       [tex]v_{o} = 84.1 km/h*\frac{1h}{3600s} *\frac{1000m}{1km} = 23.4 m/s (2)[/tex]

      [tex]v_{f} = 15.8 km/h*\frac{1h}{3600s} *\frac{1000m}{1km} = 4.4 m/s (3)[/tex]

Replacing (2) and (3) in (1), since Δx =350m, we can solving for a:

       [tex]a = \frac{(4.4m/s)^{2} - (23.4m/s)^{2}}{2*350m} = -0.76 m/s2 (4)[/tex]

In order to get the time, we can simply use the definition of acceleration, and rearrange terms:

       [tex]t =\frac{v_{f}-v_{o}}{a} = \frac{(4.4m/s)-(23.4m/s)}{-0.76m/s2} = 25.0 s (5)[/tex]

A student swings a 0.5kg rubber ball attached to a string over her head in a horizontal, circular
path. The string is 1.5 meters long and in 60 seconds the ball makes 120 complete circles.
What is the velocity of the ball?
What is the ball’s centripetal acceleration?
What is the ball's centripetal force?

Answers

Answer:

The balls velocity is 1 divided by 3

The velocity of the ball is 18.85 m/s.

The ball’s centripetal acceleration is 236.87 m/s².

The ball's centripetal force is  118.44 Newton.

What is centripetal acceleration?

Centripetal acceleration is a characteristic of an object's motion along a circular path. Centripetal acceleration applies to any item travelling in a circle with an acceleration vector pointing in the direction of the circle's center.

Given parameters:

length of the string: l = 1.5 meters.

Time interval = 60 seconds.

Total number of complete rotation = 120.

Hence, the velocity of the ball = 120×2π×1.5/60 m/s

= 18.85 m/s.

The ball’s centripetal acceleration = (velocity)²/ radius

= (18.85)²/1.5 m/s²

= 236.87 m/s²

The ball's centripetal force = mass × centripetal acceleration

= 0.5 × 236.87 Newton

= 118.44 Newton

Learn centripetal acceleration here:

https://brainly.com/question/14465119

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