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3 years ago

Diego hypothesizes that the Earth wobbles on its axis in a pattern that is repeated every 20,000 years.

Physics

2 answers:

vichka [17]3 years ago

5 0

I’m not sure but I think it’s D because we don’t have 20,000 years to make observations

daser333 [38]3 years ago

4 0

I believe I am leading towards D

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Why are metals sometimes added to gold?

Komok [63]

Because solo gold isn't strong material. But with admixture it's stronger.

7 0

4 years ago

Read 2 more answers

The Doppler effect using ultrasonic waves of frequency 2.25 × 106 Hz is used to monitor the heartbeat of a fetus. A (maximum) be

miss Akunina [59]

Answer:

$v = 2.88 \times 10^7 m/s$

Explanation:

As per Doppler's effect we know that the frequency of the sound that is observed by the detector is the reflected sound

This reflected sound is given as

$f' = f (\frac{v - v_h}{v + v_h})$

$f' = 2.25\times 10^6(\frac{v - 1540}{v + 1540})$

so we know that the beat frequency is

$\Delta f = 240 Hz$

so we will have

$f - f' = \Delta f$

$2.25 \times 10^6 - 2.25\times 10^6(\frac{v - 1540}{v + 1540}) = 240$

$1 - (\frac{v - 1540}{v + 1540}) = 1.07 \times 10^{-4}$

so we have

$0.99989 = (\frac{v - 1540}{v + 1540})$

$1.99989\times 1540 = 1.067 \times 10^{-4} v$

$v = 2.88 \times 10^7 m/s$

4 0

4 years ago

an object is moving with a velocity 10 m/s but its slowing down.After 2m it has stoppes.What was the acceleration?

s344n2d4d5 [400]

Answer:

Explanation

distance= speedx time

time= 2m/(10m/s) =0.2s

a = v-u/t

a = 0-(10m/s)/0.2s

a= -50m/s2

5 0

4 years ago

An ion's position vector is initially r with arrow = 7.0i hat â 7.0j + 1.0k, and 5.0 s later it is r with arrow = 7.0i hat + 7.0

harkovskaia [24]

<h2>Answer:</h2>

Shown in the explanation

<h2>Explanation:</h2>

Position vector of a particle at a given instant is given by:

$\vec{r}=x\hat{i}+y\hat{j}+z\hat{k}$

On the other hand, the average velocity is the change in the particle’s position vector divided by time interval:

$\vec{v}=\frac{\Delta \vec{r}}{\Delta t}=\frac{\vec{r_{2}}-\vec{r_{1}} }{t_{2}-t_{1}} \\ \\ \\ Where: \\ \\ \\ \vec{r_{1}}: Initial \ position \\ \\ \vec{r_{2}}: Final \ position \\ \\ t_{1}:Initial \ time \\ \\ t_{2}:Final \ time$

So we have:

$\vec{r_{1}}=7\hat{i}+7\hat{j}+1\hat{k} \\ \\ \vec{r_{2}}=7\hat{i}+7\hat{j}+8\hat{k} \\ \\ \\ Then: \\ \\ \Delta \vec{r} = \vec{r_{2}}-\vec{r_{1}}=7\hat{i}+7\hat{j}+8\hat{k}-(7\hat{i}+7\hat{j}+1\hat{k}) \\ \\ \Delta \vec{r}=7\hat{k} \\ \\ \\ We \ also \ know: \\ \\ \Delta t=5s$

Finally, the average velocity is:

$\vec{v}=\frac{\Delta \vec{r}}{\Delta t} \\ \\ \\ \vec{v}=\frac{7\hat{k}}{5} \\ \\ \boxed{\vec{v}=\frac{7}{5}\hat{k} \ units/s}$

3 0

4 years ago

Lena is playing with a remote-controlled car in her backyard. She knows that the car uses a wheel and axle to move. What is the

melomori [17]

Answer:

C. chemical energy from the batteries

Explanation:

Remote-controlled car or commonly called RC cars are toy vehicles that are controlled or propelled to move from a distance by a wire-connected remote that sends radiowaves to the receiver. According to this question involving the remote-controlled car Lena is playing with, a transmitter from the remote propels the wheel and axle to make the car move.

The car contains a battery cell that uses it's chemical energy as a source of power for the wheel and axle system. Hence, the chemical energy from the batteries of a remote-controlled car powers the wheel and axle to make the car move.

7 0

3 years ago