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3 years ago

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Scientific knowledge is both long lasting and open to change. In your own words, explain why scientific knowledge should be re-e

xamined and re-tested from time to time. Include two examples that will support your response.

2 answers:

Nostrana [21]3 years ago

7 0

Science is open to change because scientists agree that there are no absolute truths, only the best explanations for the data
there are specifically two cases when science can change: -new data is discovered (for example new skeleton makes us revise the known history of homo species)
-a new model is proposed that fits the data better (such as the heliocentric model of Copernicus)

Leviafan [203]3 years ago

3 0

Answer:

Open to change

Explanation:

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Which expressions correctly represent variations of Ohm's law? Check all that apply.

navik [9.2K]

Answer:

V = IR

R = V/I

I = V/R

Explanation:

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3 years ago

Two billion people jump up in the air at the same time with an average velocity of 7.0 m/sec. If the mass of

maria [59]

P=m x v =60 x 7.0= 420
total momentum = 420 x 2,000,000,000=dnt have a calculator
thier effect would shake the earth and kill some organism because they jump up at the same time and they wil probably land the same time .

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3 years ago

Read 2 more answers

Water waves in a small tank are .06 m long. They pass a given point at a rate of 14.8 waves every three seconds. What is the spe

snow_lady [41]

Answer:

Speed = 0.296m/2

Period = 0.203 s

Explanation:

If by 'long' you mean the wavelength of the waves, then the wavelength $\lambda=0.06m$ .

The frequency $f$ of the waves is 14.8 waves every 3 seconds or

$f=14.8/3 =4.33Hz$ .

Now the relationship between wavelength $\lambda$ , frequency $f$ and speed $v$ of the waves is:

$v=\lambda f$

We put in the values $\lambda=0.06m$ and $f=4.933Hz$ and get:

$\boxed{v=0.06*4.922=0.296m/s}$

Now the period $T$ is just the inverse of the frequency, or

$T=\frac{1}{f}$

$\boxed{T=\frac{1}{4.933}=0.203\:seconds }$

4 0

3 years ago

To calculate the ideal mechanical advantage of a lever divide the input arm by the

Ivanshal [37]

To calculate the ideal mechanical advantage of a lever divide the input arm by the output arm.
Mechanical advantage is the amount by which a machine can multiply an input force, calculated by dividing output Force in newtons by input force in newtons, while the ideal mechanical advantage is the mechanical advantage of a machine that has no friction, calculated by dividing the input distance by the output distance.

6 0

3 years ago

During a testing process, a worker in a factory mounts a bicycle wheel on a stationary stand and applies a tangential resistive

Katyanochek1 [597]

Answer:

The force is $F = 1041.7N$

Explanation:

The moment of Inertia I is mathematically evaluated as

$I = MR_A^2$

Substituting $1.9kg$ for M(Mass of the wheel) and $\frac{66cm}{2} * \frac{1m}{100cm} = 0.33m$ for $R_A$ (Radius of wheel)

$I = 1.9 * 0.33^2$

$= 0.207kgm^2$

The torque on the wheel due to net force is mathematically represented as

$\tau = FR_B - F_rR_A$

Substituting 135 N for $F_r$ (Force acting on sprocket), $\frac{8.7cm}{2} * \frac{1m}{100cm} = 0.0435m$ for $R_B$ (radius of the chain) and F is the force acting on the sprocket due to the chain which is unknown for now

$\tau = F (0.0435) - 135 (0.33)$

This same torque due to the net force is the also the torque that is required to rotate the wheel to have an angular acceleration of $\alpha = 3.70 rad/s^2$ and this torque can also be represented mathematically as

$\tau = \alpha I$

Now equating the two equation for torque

$F (0.0435) - 135 (0.33) = \alpha I$

Making F the subject

$F = \frac{\alpha I + (135*0.33) }{0.0435}$

Substituting values

$F = \frac{(3.70 * 0.207) + (135*0.33)}{0.0435}$

$= 1041.7N$

4 0

3 years ago