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NNADVOKAT [17]
2 years ago
9

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

3 0
3 years ago
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
Lesechka [4]

Answer:

Subtract the atomic number from the mass number

Explanation:

The number of neurons in an atom is equal to the difference between the atomic number and the mass number

5 0
1 year ago
Increasing the # of pulleys increases the _______ but decreases the amount of ______ applied
Maksim231197 [3]

Distance, Force

<u>Explanation:</u>

1)  Increasing the load will add to the friction on the bearings of the pulleys, thus reducing the efficiency of the system.  The ideal mechanical advantage won't change since the ideal mechanical advantage ignores friction.

2)  Increasing the number of pulleys will increase the ideal mechanical advantage, but because of friction it will decrease the efficiency.  The more pulleys that are turning, the more friction there is, and the less efficient the system will be.

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.

8 0
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

For Train 1 Velocity of the observer,

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},

The Equation is

f_{o}=f_{s}(\dfrac{v+v_{o}}{v -v_{s}})

Where,

v = velocity of sound in air = 343 m/s

Substituting the values we get

f_{o}=500(\dfrac{343+40.28}{343 -25})=500\times 1.205=602.64\approx 603\ Hz

Therefore,

The frequency heard by the engineer on train 1

f_{o}=603\ Hz

7 0
3 years ago
Which of the following cannot be used to describe a longitudinal wave?
alex41 [277]

Answer:

crest

hope It helped you!

8 0
2 years ago
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