Ask question

Ask question

All categories

3 years ago

9

A river flows due south with a speed of 2.0 m/s. You steer a motorboat across the river; your velocity relative to the water is

4.2 m/s due east. The river is 500 m wide. (a) What is your velocity (magnitude and direction) relative to the earth? (b) How much time is required to cross the river? (c) How far south of your starting point will you reach the opposite bank?

1 answer:

neonofarm [45]3 years ago

6 0

Answer:

a) 25.5°(south of east)

b) 119 s

c) 238 m

Explanation:

solution:

we have river speed $v_{r}$ =2 m/s

velocity of motorboat relative to water is $v_{m/r}$ =4.2 m/s

so speed will be:

a) $v_{m}$ = $v_{r}$ + $v_{m/r}$

solving graphically

$v_{m}=\sqrt{v^2_{r}+v^2_{m/r}}$

=4.7 m/s

Ф= $tan^{-1} (\frac{v_{r}}{v_{m/r}} )$

=25.5°(south of east)

b) time to cross the river: t= $\frac{w}{v_{m/r}}$ = $\frac{500}{4.2}$ =119 s

c) d= $v_{r}t$ =(2)(119)=238 m

note :

pic is attached

You might be interested in

If an object absorbs all colors but red, we see

julia-pushkina [17]

[I researched for you, since I am not in that particular level to know that knowledge yet. I assure this is accurate info :)]

The answer is A, red.
"Remember, the color you see is light REFLECTING off the surface of that object. If all colors are absorbed in to the surface EXCEPT red, red must be reflected, and you'll see red." - Yahoo User @Chap

8 0

2 years ago

A circular loop of wire with a radius of 15.0cm and oriented in the horizontal xy-plane is located in a region of uniform magnet

Drupady [299]

Answer:

See answer

Explanation:

The area of the circular loop is given by:

$A = \pi r^2$

The magnetic flux is given by:

$\phi = \int \vec{B} \cdot d\vec{A}$

$d\vec{A}$ is parallel to $\vec{B}$ and $\vec{B}$ is constant in magnitude and direction therefore:

$\phi = \int \vec{B} \cdot d\vec{A}= \int BdAcos(0)= B\int dA= B*(\pi r^2)= \pi Br^2$

Part A)

initially the flux is $\phi =\pi B r^2$

after the interval $\Delta t= 2.4 [m/s]$

the flux is

$\phi = 0$

now, the EMF is defined as:

$\epsilon =- \frac{d \phi}{dt}$ ,

if we consider $\Delta t= 2.4 [m/s]$ very small then we can re-write it as:

$\epsilon =- \frac{\Delta \phi}{\Delta t}$

$\Delta \phi = 0 - \pi B r^2=-\pi (1.7) (0.15)^2=-0.12$

then:

$\epsilon =- \frac{-0.12}{0.0024} = 50 [V]$

Part B)

When looked down from above, the current flows counter clockwise, according to the right hand rule, if you place your thumb upwards (the direction of the magnetic field) and close your fingers, then the current will flow in the direction of your fingers.

3 0

3 years ago

A student is creating a table with properties of electromagnetic and mechanical waves.

katen-ka-za [31]

Answer:

The property of the wave marked X is related to the source of the wave

Explanation:

The source of of origin of waves

Electromagnetic wave are waves that consists of varying electric and magnetic field that vibrate perpendicular to each other and to the direction of propagation of the wave and they are therefore transverse waves and transfer energy

Electromagnetic waves originate from the vibration of charged particles that gives off varying electric and magnetic fields

Mechanical waves are defined as waves that require a material medium such as air, water, metal, plastic, stretched leather, or wood to propagate

Mechanical waves originate from vibration of the particles of a medium

Sound waves which is a form of longitudinal mechanical waves that propagates by the vibration of the particles of a given medium about a point parallel to the direction of propagation of the wave.

8 0

3 years ago

What is mass?Explain

Alexxx [7]

Answer:

The term mass is used to refer to the amount of matter in any given object For instance, a person or object may be weightless on the moon because of the lack of gravity but that same person or object maintains the same mass regardless of location

Explanation:

8 0

2 years ago

The ph balance is maintained by which organ?

Lena [83]

The Kidneys And Lungs.

7 0

3 years ago