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3 years ago

a sound wave travels at 330 m/sec and has a wavelenght of 2meters. calcuate the frequency and period

1 answer:

7 0

The frequency of any wave is (speed) / (wavelength).

Frequency = (330 m/s) / (2m) = 165 per second = <em>165 Hz</em>.

Period = 1 / frequency = 1 / (165 per second) = <em>0.0061 second </em>

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Your shopping cart has a mass of 65 kilograms, In order to accelerate the shopping cart down an aisle at 0.3 m/sec2, what force

garri49 [273]

Remember Newton's second law: F=ma

to get the force in newtons, mass should be in kg and acceleration in m/s^2

conveniently, we don't need to convert units

we just need to multiply the two to get the force

65* 0.3 = 19.5 kg m/s^2 or N

if significant digit is an issue, the least number if sig figs is 1 so the answer would be 20 N

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2 years ago

You set your stationary bike on a high 80-N friction-like resistive force and cycle for 30 min at a speed of 8.0 m/s . Your body

stellarik [79]

A) The change in internal chemical energy is $1.15\cdot 10^7 J$

B) The time needed is 1 minute

Explanation:

First of all, we start by calculating the power output of you and the bike, given by:

$P=Fv$

where

F = 80 N is the force that must be applied in order to overcome friction and travel at constant speed

v = 8.0 m/s is the velocity

Substituting,

$P=(80)(8.0)=640 W$

The energy output is related to the power by the equation

$P=\frac{E}{t}$

where:

P = 640 W is the power output

E is the energy output

$t = 30 min \cdot 60 = 1800 s$ is the time elapsed

Solving for E,

$E=Pt=(640)(1800)=1.15\cdot 10^6 J$

Since the body is 10% efficient at converting chemical energy into mechanical work (which is the output energy), this means that the change in internal chemical energy is given by

$\Delta E = \frac{E}{0.10}=\frac{1.15\cdot 10^6}{0.10}=1.15\cdot 10^7 J$

From the previous part, we found that in a time of

t = 30 min

the amount of internal chemical energy converted is

$E=1.15\cdot 10^7 J$

Here we want to find the time t' needed to convert an amount of chemical energy of

$E'=3.8\cdot 10^5 J$

So we can setup the following proportion:

$\frac{t}{E}=\frac{t'}{E'}$

And solving for t',

$t'=\frac{E't}{E}=\frac{(3.8\cdot 10^5)(30)}{1.15\cdot 10^7}=1 min$

Learn more about power and energy:

brainly.com/question/7956557

#LearnwithBrainly

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2 years ago

How did people studying lunar eclipses learn that Earth is round?

qwelly [4]

Answer:

Scientists have studied eclipses since ancient times. Aristotle observed that the Earth's shadow has a circular shape as it moves across the moon. He posited that this must mean the Earth was round. Another Greek astronomer named Aristarchus used a lunar eclipse to estimate the distance of the Moon and Sun from Earth

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2 years ago

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The plain flight covers 400 miles in the first hour. As you approach the landing site, it takes you an hour to cover the last 20

tatyana61 [14]

that is an example of negative acceleration because it is slowing down

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2 years ago

A 1000-kg car moving at 10 m/s brakes to a stop in 5 s. the average braking force is

Marina86 [1]

To calcculate the braking force of the car moving, we use Newton's second law of motion which relates the acceleration and the force of an object moving. The force of an object moving is directly proportional to its acceleration and the proportionality constant is the mass of the object. It is expressed as:

Force = ma

Acceleration is the rate of change of the velocity of a moving object. We calculate acceleration from the velocity and the time given above.

a = (10 m/s) / 5 s = 2 m/s^2

So,
Force = ma
Force = 1000 kg ( 2 m/s^2 )
Force = 2000 kg m/s^2 or 2000 N

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3 years ago