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ollegr [7]
2 years ago
13

A man is crossing a river of width 100 m on a motorboat. The velocity of the motor boat is 4 m/s eastward and the velocity of th

e water current is 3 m/s northward.
What is the resultant velocity of the boat and how much time will it take for the man to reach the other shore of the river?

A) The resultant velocity of the motor boat is 5 m/s and it takes 20s to cross the river.

B) The resultant velocity of the motor boat is 25 m/s and it takes 5s to cross the river.

C) The resultant velocity of the motor boat is 6 m/s and it takes 20s to cross the river.

D) The resultant velocity of the motor boat is 4 m/s and it takes 33s to cross the river.
Physics
1 answer:
Airida [17]2 years ago
5 0

By the Pythagorean theorem we get 3^2+4^2=5^2. Thus the resultant velocity will be 5 m/s.

However there is a typo in the choices. It should take 25 seconds to cross the river, not 20 seconds, since the boat actually travels 125 meters due to the water current, and 125/5 = 25 seconds.

Alternatively  you can calculate the eastward component of travel and get 100 / 4 = 25 seconds.


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Given the vector A with components Ax = 2.00, Ay = 6.00, the vector B with components Bx = 2.00, By = 22.00, and the vector D =
nekit [7.7K]

Answer:

<em>The magnitude of vector d is 16 and the angle with the x-axis is 270°</em>

Explanation:

<u>Operations With Vectors</u>

Given two vectors in rectangular components:

\vec a=(ax,ay)\ ,\  \vec b=(bx,by)

The sum of the vectors is:

\vec a+\vec b=(ax+bx,ay+by)

The difference between the vectors is:

\vec a-\vec b=(ax-bx,ay-by)

The magnitude of \vec a is:

|\vec a|=\sqrt{ax^2+ay^2}

The angle \vec a makes with the horizontal positive direction is:

\displaystyle \tan\theta=\frac{ay}{ax}\\

The question provides the vectors:

\vec a=(2,6)

\vec b=(2,22)

\vec d=\vec a-\vec b

Calculate:

\vec d=(2,6)-(2,22)=(0,-16)

The magnitude of \vec d is:

|\vec d|=\sqrt{0^2+(-16)^2}=\sqrt{0+256}=16

The angle is calculated by:

\displaystyle \tan\theta=\frac{-16}{0}

The division cannot be calculated because the denominator is zero. We need to estimate the correct angle by looking at the components of the vector. Since the x-coordinate is zero and the y-coordinate is negative, the vector points downwards (south), thus the angle must be -90° or 270° if the range goes from 0° to 360°.

The magnitude of vector d is 16 and the angle with the x-axis is 270°

4 0
3 years ago
Why do you think a clothes dryer requires a 220-volt outlet, while a toaster only requires a 110-volt outlet?
hammer [34]

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3 years ago
The kinetic energy of a book on a shelf is equal to the work done to lift the book to the shelf. t/f
Svet_ta [14]
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7 0
3 years ago
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A beam of light traveling through a liquid (of index of refraction n1 = 1.47) is incident on a surface at an angle of θ1 = 59° w
frosja888 [35]

Answer:

(a) n_{2} = \frac{n_{1}sin\theta_{1}}{sin\theta_{2}}

(b) n_{2} = 1.349

(c) v_{1} = 2.04\times 10^{8}\ m/s

(d) v_{2} = 2.22\times 10^{8}\ m/s

Solution:

As per the question:

Refractive index of medium 1, n_{1} = 1.47

Angle of refraction for medium 1, \theta_{1} = 59^{\circ}

Angle of refraction for medium 2, \theta_{1} = 69^{\circ}

Now,

(a) The expression for the refractive index of medium 2 is given by using Snell's law:

n_{1}sin\theta_{1} = n_{2}sin\theta_{2}

where

n_{2} = Refractive Index of medium 2

Now,

n_{2} = \frac{n_{1}sin\theta_{1}}{sin\theta_{2}}

(b) The refractive index of medium 2 can be calculated by using the expression in part (a) as:

n_{2} = \frac{1.47\times sin59^{\circ}}{sin69^{\circ}}

n_{2} = 1.349

(c) To calculate the velocity of light in medium 1:

We know that:

Refractive\ index,\ n = \frac{Speed\ of\ light\ in vacuum,\ c}{Speed\ of\ light\ in\ medium,\ v}

Thus for medium 1

n_{1} = \frac{c}{v_{1}

v_{1} = \frac{c}{n_{1} = \frac{3\times 10^{8}}{1.47} = 2.04\times 10^{8}\ m/s

(d) To calculate the velocity of light in medium 2:

For medium 2:

n_{2} = \frac{c}{v_{2}

v_{2} = \frac{c}{n_{1} = \frac{3\times 10^{8}}{1.349} = 2.22\times 10^{8}\ m/s

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Answer:

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