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natta225 [31]
3 years ago
14

Vector A has a magnitude of 25 units and points in the positive y-direction. When vector B is added to A, the resultant vector A

B points in the negative y-direction with a magnitude of 15 units. Find the magnitude and direction of B.
Physics
1 answer:
bixtya [17]3 years ago
3 0

Answer:

B= -40

The negative sign indicates the reverse direction to that of vector A.That is it is in the third quadrant.

Explanation:

Th resultant vector is obtained by adding the two vectors A and B

A + B= AB

25 + B= -15

25+ 15= -B

-B = 40

B= -40

Vector B has a magnitude of 40 and points in the opposite direction to that of vector A. The negative indicates the opposite direction.

When we reverse the vector B for adding we place a negative sign with the magnitude.

A vector is quantity defined by magnitude and direction. If the direction is left out it becomes a scalar.

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A domestic water heater holds 189 L of water at 608C, 1 atm. Determine the exergy of the hot water, in kJ. To what elevation, in
Gekata [30.6K]

A.

The energy of the hot water is 482630400 J

Using Q = mcΔT where Q = energy of hot water, m = mass of water = ρV where ρ = density of water = 1000 kg/m³ and V = volume of water = 189 L = 0.189 m³,

c = specific heat capacity of water = 4200 J/kg-°C and ΔT = temperature change of water = T₂ - T₁ where T₂ = final temperature of water = 608 °C. If we assume the water was initially at 0°C, T₁ = 0 °C. So, the temperature change ΔT = 608 °C - 0 °C = 608 °C

Substituting the values of the variables into the  equation, we have

Q = mcΔT

Q = ρVcΔT

Q = 1000 kg/m³ × 0.189 m³ × 4200 J/kg-°C × 608 °C

Q = 482630400 J

So, the energy of the hot water is 482630400 J

B.

The elevation <u>the mass would have to be raised from zero elevation relative to the reference environment for its exergy to equal that of the hot water</u> is 49248 m.

Using the equation for gravitational potential energy ΔU = mgΔh where m = mass of object = 1000 kg, g = acceleration due to gravity = 9.8 m/s² and Δh = h - h' where h = required elevation and h' = zero level elevation = 0 m

Since the energy of the mass equal the energy of the hot water, ΔU = 482630400 J

So, ΔU = mgΔh

ΔU = mg(h - h')

making h subject of the formula, we have

h = h' + ΔU/mg

Substituting the values of the variables into the equation, we have

h = h' + ΔU/mg

h = 0 m + 482630400 J/(1000 kg × 9.8 m/s²)

h = 0 m + 482630400 J/(9800 kgm/s²)

h = 0 m + 49248 m

h = 49248 m

So, the elevation <u>the mass would have to be raised from zero elevation relative to the reference environment for its exergy to equal that of the hot water</u> is 49248 m.

Learn more about heat energy here:

brainly.com/question/11961649

5 0
3 years ago
an object is shot vertically upward into the air with an initial velocity of 20 m/s? which of the following correctly describes
Drupady [299]

Answer:

Answer is (C)

Explanation:

<u>For</u><u> </u><u>acceleration</u>

• If the motion is vertically, then acceleration is 9.8 m/s²

» Upward motion, acceleration is negative (-9.8)

» Downward motion, acceleration is positive (+9.8)

<u>For</u><u> </u><u>velocity</u>

{ \rm{v = u + gt}} \\ { \rm{v = 20 + ( - 9.8 \times 4)}} \\  { \rm{v =  - 19.2 \: m {s}^{ - 1} }}

5 0
2 years ago
A 25.0-kg box of textbooks rests on a loading ramp that makes an angle α with the horizontal. The coefficient of kinetic frictio
Leni [432]

Answer:

Explanation:

a ) When the box starts to slip

static friction = mg sinα

mg cosα x μ =  mg sinα (  μ is coefficient of static friction )

Tanα =  μ  = .35

α  = 19.2°

b ) Once box starts moving , kinetic friction will start applying on it

kinetic friction = mg cos19.2 x .25

= 2.31m

net force downward = mgsin19.2 - mgcos19.2 x .25

= m ( 3.22 - 2.31 )

= .91 m

acceleration downward ( a )   = .91 m / s²

c )

v² = u² + 2 a s

= 0 + 2 x .91 x 5

= 9.1

v = 3 m / s

3 0
4 years ago
Please help 9.2.1 project in science just ned an example​
olga55 [171]

Answer:

Give me what kind of example you need please so I can help you. Put it in the comments.

Explanation:

3 0
3 years ago
a grinding wheel is initially rotating with an angular velocity 5500 rad/srad/s when its motor is suddenly turned off. it comes
kiruha [24]

The angle through which the grinding wheel rotates in the first second =  <u>5300 rad</u>

Angular velocity is, the time charge at which an object rotates, or revolves, about an axis, or at which the angular displacement between our bodies changes. within the discern, this displacement is represented via the angle θ among a line on one body and a line on the alternative.

The angular velocity is described as the charge of trade of the angular position of a rotating body. Linear speed is defined because the charge of change of displacement with respect to time whilst the item moves alongside a straight course.

Initial angular velocity of the grinding wheel = ω1 = 5500 rad/s

Final angular velocity of the grinding wheel = ω2 = 0 rad/s   (Comes to rest)

Time is taken by the grinding wheel to come to rest = T = 10 sec

Angular acceleration of the grinding wheel = α

2 = ω1 + αT

0 = 5500 + α(10)

α = - 400 rad/s2

Negative as it is deceleration.

The angle through which the grinding wheel rotates in the first second = θ

Time period = T1 = 1 sec

θ = ω₁T1 + αT1²/2

θ = (5500)(1) + (-400)(1)²/2

θ = 5300 rad

The angle through which the grinding wheel rotates in the first second =  <u>5300 rad</u>

Learn more about angular velocity here:-brainly.com/question/6860269

#SPJ4

5 0
1 year ago
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