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2 years ago

Need help with dot product

Physics

1 answer:

slavikrds [6]2 years ago

5 0

$\textbf{A}\cdot\textbf{B} = 11.5$

Explanation:

The dot product between two vectors $\textbf{A}$ and $\textbf{B}$ is defined as

$\textbf{A}\cdot\textbf{B} = AB\cos{\theta}$

where A and B are the magnitudes of the vectors $\textbf{A}$ and $\textbf{B},$ respectively and $\theta$ is the angle between the two. Since A = 3, B = 5 and $\theta = 40°,$ the dot product $\textbf{A}\cdot\textbf{B}$ is

$\textbf{A}\cdot\textbf{B} = (3)(5)(0.766) = 11.5$

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The constant forces F1 = 8 + 29 + 32 N and F2 = 48 - 59 - 22 N act together on a particle during a displacement from the point A

steposvetlana [31]

Answer:

- 600 J

Explanation:

A (20, 15, 0 ) m

B (0, 0, 7) m

$\overrightarrow{F_{1}}=8\widehat{i}+29\widehat{j}+32\widehat{k}$

$\overrightarrow{F_{2}}=48\widehat{i}-59\widehat{j}-22\widehat{k}$

Net force

$\overrightarrow{F}=\overrightarrow{F_{1}}+\overrightarrow{F_{2}}$

$\overrightarrow{F}}=\left ( 8+48 \right )\widehat{i}+\left ( 29-59 \right )\widehat{j}+\left ( 32-22 \right )\widehat{k}$

$\overrightarrow{F}}=56\widehat{i}-30\widehat{j}+10\widehat{k}$

$\overrightarrow{S}=\overrightarrow{OB}-\overrightarrow{OA}$

$\overrightarrow{S}=\left ( 0-20 \right )\widehat{i}+\left ( 0-15 \right )\widehat{j}+\left ( 7-0 \right )\widehat{k}$

$\overrightarrow{S}=-20\widehat{i}-15\widehat{j}+7\widehat{k}$

Work done is defined as

$W = \overrightarrow{F}.\overrightarrow{S}$

$W = \left ( 56\widehat{i}-30\widehat{j}+10\widehat{k} \right ).\left (-20\widehat{i}-15\widehat{j}+7\widehat{k} \right )$

W = -1120 + 450 + 70

W = - 600 J

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A student wants to draw a model of an atom. Which statement describes how to find the number of neutrons to include in the model

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Answer:

Subtract the atomic number from the mass number

Explanation:

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Increasing the # of pulleys increases the _______ but decreases the amount of ______ applied

Maksim231197 [3]

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<u>Explanation:</u>

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3) Work = force x distance, and what machines do is alter the amount of force you can apply while at the same time reducing the distance moved by the same factor. For instance, a jack multiplies the force you apply by a factor of 100, when you push down on the handle of the jack 100 cm, the car will only go up 1 cm. So the force x distance is the same 100 x force x 1/100 x distance.

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3 years ago

Two trains on separate tracks move toward each other. Train 1 has a speed of 145 km/h; train 2, a speed of 72.0 km/h. Train 2 bl

tekilochka [14]

Answer:

Therefore,

The frequency heard by the engineer on train 1

$f_{o}=603\ Hz$

Explanation:

Given:

Two trains on separate tracks move toward each other

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$v_{o}=145\ km/h=145\times \dfrac{1000}{3600}=40.28\ m/s$

For Train 2 Velocity of the Source,

$v_{s}=90\ km/h=90\times \dfrac{1000}{3600}=25\ m/s$

Frequency of Source,

$f_{s}=500\ Hz$

To Find:

Frequency of Observer,

$f_{o}=?$ (frequency heard by the engineer on train 1)

Solution:

Here we can use the Doppler effect equation to calculate both the velocity of the source $v_{s}$ and observer $v_{o}$ , the original frequency of the sound waves $f_{s}$ and the observed frequency of the sound waves $f_{o}$ ,