Physics help! I really need this homework done:

A camera operator is filming a nature explorer in the Rocky Mountains. The explorer needs to swim across a river to his campsite

julia-pushkina [17]

Answer:

<em>a. Angle= 28.82°</em>

<em>b. Approved. He will get cold but he should be able to make it across</em>

Explanation:

Velocity Vector

The velocity is a physical quantity that measures how fast or slow at a particular direction some object is moving. It must be expressed as a vector with both a magnitude and direction. If the object is confined to move in one direction, then we can use the speed as the scalar (magnitude only) equivalent of the velocity.

a.

The explorer wants to swim across a river to his campsite, as shown in the image below. The river has a velocity vr and the explorer can swim at ve in still water. If he swam directly to the campsite, he would end up in a point below it because the river would push him down. He must swim with a velocity such that he overcomes the stream but he advances to its objective. Let's call the angle he must swim at respect to the shoreline to achieve his goal. The explorer's velocity can be decomposed in its rectangular components vx and vy. To overcome the river's velocity:

$v_{ey}=v_r$

We can compute the vertical component of the explorer's velocity as

$v_{ey}=|v_e|cos\alpha$

Thus

$v_r=|v_e|cos\alpha$

Solving for $\alpha$

$\displaystyle cos\alpha=\frac{v_r}{|v_e|}$

$\displaystyle cos\alpha=\frac{0.665}{0.759}=0.876$

Then we have the angle is

$\alpha=28.82^o$

b.

The horizontal component of the explorer's velocity is

$v_{ex}=0.759sin28.82^o$

$v_{ex}=0.366\ m/s$

This is the real velocity the explorer is having directly to the campsite

Knowing that

$\displaystyle v=\frac{x}{t}$

Solving for t

$\displaystyle t=\frac{x}{v}$

Calculating the time it takes the explorer to cross the river

$\displaystyle t=\frac{29.3}{0.366}$

$t=80\ sec$

Since this value is less than the limit value of hypothermia (300 sec), the decision is

Approved. He will get cold but he should be able to make it across

3 0

3 years ago

What is the function or the skeletal system hdbdb

yKpoI14uk [10]

Explanation:

Hope its helps u

if wrong then sry

5 0

3 years ago

The efficiency of a squeaky pulley system is 73 percent. The pulleys are usedto raise a mass to a certain height. What force is

larisa86 [58]

The efficiency of the machine is defined as

$\eta = \frac{W_{out}}{W_{in}}$

Here

Work out is the work output and Work in is the work input

To find the Work in we have then

$W_{in} = \frac{W_{out}}{\eta}$

$W_{in} = \frac{mgh}{\eta}$

Replacing with our values

$W_{in} = \frac{(58)(9.8)(3)}{73\%}$

$W_{in} = 2335.89J$

The work done by the applied force is

W = Fd

Here,

F = Force

d = Distnace

Rearranging to find F,

$F = \frac{W}{d}$

$F = \frac{2335.89J }{18}$

F = 129.77N

Therefore the force exerted on the machine after rounding off to two significant figures is 130N

8 0

3 years ago

A wooden block of dimensions of 6 cm ⨯ 6 cm ⨯ 15 cm floats with the long axis oriented horizontally and the of the square faces

schepotkina [342]

Explanation:

(a) Formula to calculate volume of the submerged wooden block is as follows.

$V_{sub} = l \times w \times d$

It is given data of the wooden block is as follows.

depth = 7.96 cm, length (l) = 6 cm

width (w) = 4 cm,

So, we will calculate the volume of the submerged wooden block as follows.

$V_{sub} = l \times w \times d$

= $6 \times 6 \times 7.96$

= 286.56 $cm^{3}$

Hence, the submerged volume of the block is 286.56 $cm^{3}$ .

(b) Expression for the buoyant force acting on the wooden block is as follows.

$F_{B} = \rho_{w} g V_{sub}$

And, expression for the force of gravity of the wooden block is as follows.

$F_{g} = m_{b}g$

As the wooden block is floating on the water hence, buoyant force is balanced by the weight of the block.

$F_{g} = F_{B}$

Hence, mass of the wooden block will be calculated as follows.

$F_{g} = F_{B}$

$m_{b}g = \rho_{w}gV_{sub}$

$m_{b} = \rho_{w}V_{sub}$

= $997 kg/m^{3} \times 286.56 cm^{3}$

= $997 kg/m^{3} \times 286.56 \times 10^{-6} m^{3}$

= 0.02857 kg

Therefore, mass of the given block is 0.02857 kg

(c) Expression for the density of the block is as follows.

$\rho_{b} = \frac{m_{b}}{V_{b}}$

Now, expression for the total volume of the wooden block is as follows.

$V_{b} = l \times w \times h$

Hence, density of the given block is as follows.

$\rho_{b} = \frac{m_{b}}{V_{b}}$

= $\frac{m_{b}}{lwh}$

= $\frac{0.02857 kg}{4 \times 4 \times 15}$

= $1.19 \times 10^{-4} kg/cm^{3}$

Therefore, density of the given block is $1.19 \times 10^{-4} kg/cm^{3}$ .

3 0

3 years ago

The forced exerted on an object are shown. If the object moves right, which of the following is a possible value of F? Ignore my

Deffense [45]

Answer:

5N

Explanation:

Because if it moves to the right, that means F is weak and 6N is STRONK

8 0

3 years ago

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