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3 years ago

Solids have a definite shape and volume

Physics

1 answer:

Black_prince [1.1K]3 years ago

7 0

Yes that is true, toothpaste has been very debatable over the years. (I really need Brainliest.) Hope this helps!!!!

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10. A sound wave has a frequency of 400 Hz and a wavelength of 20 meters. What is the speed?

Dmitry [639]

Speed of wave is 8000 m/s.

Answer:

Explanation:

Speed is the measure of ratio of distance to time taken to cover that distance. In other words, speed is the measure of how fast the object can be move in a given time interval. So in this case, the wave is considered as object . And wave consists of wavelength in place of distance and frequency as reciprocal of time interval.

So speed of wave is calculated as the product of wavelength and frequency.

As the wavelength is given as 20 m and the frequency is given as 400 Hz, then the speed will be

Speed = wavelength × Frequency = 20 × 400

Speed of wave = 8000 m/s.

So speed of wave is 8000 m/s.

6 0

4 years ago

Jerri is planning to rebuild the engine of an antique car. She has chosen all the materials she needs including a high quality s

Strike441 [17]

Oil keeps the moving metal parts of an engine smoothly rubbing together through lubrication. Just like with other mechanical devices, energy can be lost due to friction caused by lack of proper lubrication. When an engine is running on old or insufficient oil, more friction and heat is produced between the rubbing moving parts. A decline in gas mileage follows this since the fuel takes more than usual to do the same task.

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3 years ago

Read 2 more answers

What kind of model is shown below?

Kay [80]

Still there ain’t no picture

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3 years ago

Read 2 more answers

Subduction occurs as a result of:__________

lutik1710 [3]

Answer:

a) Gravity pulling the older and denser lithosphere downward.

Explanation:

Earth's crust is made of plates which float on mantle . Plates are of two types

1 ) oceanic plates which are older and heavier 2 ) continental plates which are lighter . Continents are situated on continental plates. Due to relative motion , oceanic plate, because of its heavy weight, goes under lighter continental plate . This is called subduction.

6 0

3 years ago

A boat crossing a 153.0 m wide river is directed so that it will cross the river as quickly as possible. The boat has a speed of

Lynna [10]

We have the relation

$\vec v_{B \mid E} = \vec v_{B \mid R} + \vec v_{R \mid E}$

where $v_{A \mid B}$ denotes the velocity of a body A relative to another body B; here I use B for boat, E for Earth, and R for river.

We're given speeds

$v_{B \mid R} = 5.10 \dfrac{\rm m}{\rm s}$

$v_{R \mid E} = 3.70 \dfrac{\rm m}{\rm s}$

Let's assume the river flows South-to-North, so that

$\vec v_{R \mid E} = v_{R \mid E} \, \vec\jmath$

and let $-90^\circ < \theta < 90^\circ$ be the angle made by the boat relative to East (i.e. -90° corresponds to due South, 0° to due East, and +90° to due North), so that

$\vec v_{B \mid R} = v_{B \mid R} \left(\cos(\theta) \,\vec\imath + \sin(\theta) \, \vec\jmath\right)$

Then the velocity of the boat relative to the Earth is

$\vec v_{B\mid E} = v_{B \mid R} \cos(\theta) \, \vec\imath + \left(v_{B \mid R} \sin(\theta) + v_{R \mid E}\right) \,\vec\jmath$

The crossing is 153.0 m wide, so that for some time $t$ we have

$153.0\,\mathrm m = v_{B\mid R} \cos(\theta) t \implies t = \dfrac{153.0\,\rm m}{\left(5.10\frac{\rm m}{\rm s}\right) \cos(\theta)} = 30.0 \sec(\theta) \, \mathrm s$

which is minimized when $\theta=0^\circ$ so the crossing takes the minimum 30.0 s when the boat is pointing due East.

It follows that

$\vec v_{B \mid E} = v_{B \mid R} \,\vec\imath + \vec v_{R \mid E} \,\vec\jmath \\\\ \implies v_{B \mid E} = \sqrt{\left(5.10\dfrac{\rm m}{\rm s}\right)^2 + \left(3.70\dfrac{\rm m}{\rm s}\right)^2} \approx 6.30 \dfrac{\rm m}{\rm s}$

The boat's position $\vec x$ at time $t$ is

$\vec x = \vec v_{B\mid E} t$

so that after 30.0 s, the boat's final position on the other side of the river is

$\vec x(30.0\,\mathrm s) = (153\,\mathrm m) \,\vec\imath + (111\,\mathrm m)\,\vec\jmath$

and the boat would have traveled a total distance of

$\|\vec x(30.0\,\mathrm s)\| = \sqrt{(153\,\mathrm m)^2 + (111\,\mathrm m)^2} \approx \boxed{189\,\mathrm m}$

3 0

2 years ago