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ddd [48]
3 years ago
13

The value of the gravitational acceleration g decreases with elevation from 9.807 m/s2 at the sea level to 9.767 m/s2 at an alti

tude of 13000 m, where large passenger planes cruise. Determine the percentage reduction in the weight of an airplane cruising at 13000 m relative to its weight at sea level.
Physics
1 answer:
alexira [117]3 years ago
6 0

Answer: 0.41%

Explanation:

If we want to calculate the percentage decrease (the reduction) in weight of an airplane, we can use the given values of gravity, because the weight is directly proportional to the gravity acceleration.

Now the formula for the percentage decrease for ths case is:

\% weightdecrease=\frac{g_{sea}-g_{13000m}}{g_{sea}}(100)

Where:

g_{sea}=9.807 m/s^{2} is the gravity at sea level

g_{13000m}=9.767 m/s^{2} is the gravity at 13000 m

\% weightdecrease=\frac{9.807 m/s^{2} - 9.767 m/s^{2}}{9.807 m/s^{2}}(100)

\% weightdecrease=0.00407 (100)

\% weightdecrease=0.407 \% \approx 0.41 \% This is the percentage reduction in the weight of an airplane

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A rock is thrown upward from the top of a 30 m building with a velocity of 5 m/s. Determine its velocity (a) When it falls back
castortr0y [4]

Answer:

a) 5 m/s downwards

b) 17.86 m/s

c) 24.82 m/s

d) 0.228

Explanation:

We can set the frame of reference with the origin on the top of the building and the X axis pointing down.

The rock will be subject to the acceleration of gravity. We can use the equation for position under constant acceleration and speed under constant acceleration:

X(t) = X0 + V0 * t + 1/2 * a * t^2

V(t) = V0 + a * t

In this case

X0 = 0

V0 = -5 m/s

a = 9.81 m/s^2

To know the speed it will have when it falls back past the original point we need to know when it will do it. When it does X will be 0.

0 = -5 * t + 1/2 * 9.81 * t^2

0 = t * (-5 + 4.9 * t)

One of the solutions is t = 0, but this is when the rock was thrown.

0 = -5 + 4.69 * t

4.9 * t = 5

t = 5 / 4.9

t = 1.02 s

Replacing this in the speed equation:

V(1.02) = -5 + 9.81 * 1.02 = 5 m/s (this is speed downwards because the X axis points down)

When the rock is at 15 m above the street it is 15 m under the top of the building.

15 = -5 * t + 1/2 * 9.81 * t^2

4.9 * t^s -5 * t - 15 = 0

Solving electronically:

t = 2.33 s

At that time the speed will be:

V(2.33) = -5 + 9.81 * 2.33 = 17.86 m/s

When the rock is about to reach the ground it is at 30 m under the top of the building:

30 = -5 * t + 1/2 * 9.81 * t^2

4.9 * t^s -5 * t - 30 = 0

Solving electronically:

t = 3.04 s

At this time it has a speed of:

V(3.04) = -5 + 9.81 * 3.04 = 24.82 m/s

---------------------

Power is work done per unit of time.

The work in this case is:

L = Ff * d

With Ff being the friction force, this is related to weight

Ff = μ * m * g

μ: is the coefficient of friction

L = μ * m * g * d

P = L/Δt

P = (μ * m * g * d)/Δt

Rearranging:

μ = (P * Δt) / (m * g * d)

1 horsepower is 746 W

20 minutes is 1200 s

μ = (746 * 1200) / (100 * 9.81 * 4000) = 0.228

8 0
3 years ago
A kayaker needs to paddle north across a 100-m-wide harbor. The tide is going out, creating a tidal current that flows to the ea
Savatey [412]

Answer:

41.81^{\circ}

Explanation:

The tidal current flows to the east at 2.0 m/s and the speed of the kayaker is 3.0 m/s.

Let Vector \overrightarrow{OA} is the tidal current velocity as shown in the diagram.

In order to travel straight across the harbor, the vector addition of both the velocities (i.e the resultant velocity, \vec {R} must be in the north direction.

Let \overrightarrow{AB} is the speed of the kayaker having angle \theta measured north of east as shown in the figure.

For the resultant velocity in the north direction, the tail of the vector \overrightarrow {OA} and head of the vector \overrightarrow{AB} must lie on the north-south line.

Now, for this condition, from the triangle OAB

|\overrightarrow{AB}|\sin \theta=|\overrightarrow{OA}|

\Rightarrow \sin\theta=\frac{|\overrightarrow{OA}|}{|\overrightarrow{AB}|}=\frac 2 3

\Rightarrow \theta=\sin^{-1}\frac23

\Rightarrow \theta=41.81^{\circ}

Hence, the kayaker must paddle in the direction of 41.81^{\circ}  in the north of east direction.

3 0
3 years ago
The specific heat capacity of water is 4.184 J/(g.˚C). How much thermal energy is required to change the temperature of 700.0g o
worty [1.4K]

Answer:

Should be 145854.24J or:

145.9 KJ

Explanation:

I did the calculations

4 0
2 years ago
A bag of cement has a mass of 62 g. What is the mass of the bag of cement in S.I. units (kg)?
NNADVOKAT [17]

The mass of this bag of cement in S.I. units (kg) is equal to 0.062 kilograms.

<u>Given the following data:</u>

  • Mass of cement = 62 grams.

To calculate the mass of this bag of cement in S.I. units (kg):

<h3>How to convert to S.I. units.</h3>

In Science, kilograms (kg) is the standard unit of measurement or S.I. units of the mass of a physical object. Thus, we would convert the value of the mass of this bag of cement in grams to kilograms (kg) as follows:

<u>Conversion:</u>

1000 grams = 1 kilograms.

62 grams = X kilograms.

Cross-multiplying, we have:

X = \frac{62}{1000}

X = 0.062 kilograms.

Read more on mass here: brainly.com/question/13833323

8 0
2 years ago
PLz I Need Help PLZZZ ASAP
AURORKA [14]

#1

As we are increasing the frequency in the simulation the wavelength is decreasing

So if speed remains constant then wavelength and frequency depends inversely on each other

If we are in boat and and moving over very small wavelengths then these small wavelength will be encountered continuously by the boat in short interval of times

#2

As we are changing the amplitude in the simulation there is no change in the speed frequency and wavelength.

So amplitude is independent of all these parameter

Amplitude of wave will decide the energy of wave

So light of greater intensity is the light of larger amplitude

#3

In our daily life we deal with two waves

1 sound waves

2 light waves

3 0
3 years ago
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