5N 5 N 19 N 19 N Pls help look at the pic

If a = 8i + j - 2k and b = 5i - 3j + k show that a) a x b = -5i - 18j - 29k b) b X a = 50 + 18j +29k

loris [4]

Recall the definition of the cross product with respect to the unit vectors:

i × i = j × j = k × k = 0

i × j = k

j × k = i

k × i = j

and that the product is anticommutative, so that for any two vectors u and v, we have u × v = - (v × u). (This essentially takes care of part (b).)

Now, given a = 8i + j - 2k and b = 5i - 3j + k, we have

a × b = (8i + j - 2k) × (5i - 3j + k)

a × b = 40 (i × i) + 5 (j × i) - 10 (k × i)

… … … … - 24 (i × j) - 3 (j × j) + 6 (k × j)

… … … … + 8 (i × k) + (j × k) - 2 (k × k)

a × b = - 5 (i × j) - 10 (k × i) - 24 (i × j) - 6 (j × k) - 8 (k × i) + (j × k)

a × b = - 5k - 10j - 24k - 6i - 8j + i

a × b = -5i - 18j - 29k

7 0

3 years ago

Based on relative bond strengths, classify these reactions as endothermic (energy absorbed) or exothermic (energy released)

cluponka [151]

Exothermic reaction is a chemical reaction that releases energy. This reaction releases heat energy or light . In an endotermic reaction energy is used. Enthaply is the heat energy change , delta H. If the sum of the enthalpies of the reactans is greater than the products the reaction is exothermic. If the products side has a larger enthaply than the process is endothermic. So, if delta H is negative then the process is exothermic. If delta H is positive, than the process is endothermic. Exothermic are: A+BC -> AB+C A2+B2 -> 2AB Endothermic are:AB+C -> AC+B A2 + C2 -> 2AC B2+C2 -> 2BC

5 0

4 years ago

The resistivity of a metal increases slightly with increased temperature. This can be expressed as rho= rho0[1+α(T−T0)] , where

Stolb23 [73]

Answer:

At 81. 52 Deg C its resistance will be 0.31 Ω.

Explanation:

The resistance of wire = $R_T =\frac{\rho_T \ l}{A}$

Where $R_T$ =Resistance of wire at Temperature T

$\rho_T$ = Resistivity at temperature T $=\rho_0 \ [1 \ + \alpha\ (T-T_0\ )]$

Where $T_0 =20\ Deg\ C , \ \rho_0 = Constant, \alpha =3.9 \times 10^-^3 DegC^-1 \ (Given)$

l=Length of the wire

& A = Area of cross section of wire

For long and thin wire the resistance & resistivity relation will be as follows

$\frac{R_T_1}{R_T_2}=\frac{\rho_0(1+\alpha \cdot(T_1-2 0 )}{\rho_0(1+\alpha \cdot (T_2 -20 )}$

$\frac{0.25}{0.31}=\frac{1}{[1+\alpha(T-20)]}$

$1.24=1+\alpha (T-20)$

$0.24=\alpha(\ T -20 )$

$Putting\ the\ value\ of \alpha = 3.9 \times 10^-^3 DegC^-1$

T = 81.52 Deg C

4 0

3 years ago

How can you make a solution saturated

Step2247 [10]

Answer: The answer is B. Add more solute (took test)

Explanation:

5 0

3 years ago

A man walks 7 km East in 2 hours and then 2.5 km West in 1 hour. What is

madam [21]

<h2>How to solve?</h2>

We know that, Velocity is the rate of displacement covered. Displacement is the shortest path between the Initial and Final point covered by the body. So,

Velocity = Displacement / Time

And, when it comes to Average velocity, It is the total displacement by total time taken. So, By using this let's solve this question.....

<h2>Solution:</h2>

✏️ Refer to the attachment...

Let the body goes to point A that is 7 m East of the Initial point. Then it comes backward because West is opposite to East in perpendicular direction. It covers 1.5 m backwards in the same line to reach B which is the Final point.

So,

Displacement = Final point - Initial point

⇛ Displacement = 7 m - 1.5 m

⇛ Displacement = 5.5 m

Total time taken,

⇛ 2 hours + 1 hour

⇛ 3 hours

Finding Average displacement,

⇛ Total displacement / Total time taken

⇛ 5.5 m / 3 hours

⇛ 1.83333.... hours

So, the Final answer is,

$\huge{ \boxed{ \bold{ \purple{1.8 \bar{3}m}}}}$

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6 0

3 years ago