TRUE OR FALSE? >:) FOR TEENS GRADE 7 ONLY

Answer:

You should write the vectors in their proper sequence: i , j, k

If the vectors are perpendicular their dot product must be zero:

1) A dot B   is obviously zero since A and B have no common terms in i , j , k

2) looks like A = 2 i - 4 j + 3 k and B = i + 2 j + 2 k

A dot B = (2 * 1) + (-4 * 2) + (3 * 2) = 0

Note that the dot product produces a scalar with no direction (vector components)

Only i dot i, j dot j, and k dot k    have components   i dot j = zero, etc.

Answer:

24

Explanation:

If it took 3 hours to clean 6 houses than you can figure that is 2 houses per hours. so if there are 12 hours and 2 houses an hour, you multiply 12x2 and get 24. Another way to do it is to use proportions (aka two fractions that equal eachother):

  3 hours                12 hours

----------------    =    ---------------

 6 houses          number of houses

To calculate this, we can think about how we go from 3 to 12. Well, 3x4 is 12, so we got to 12 by doing multiplying by 4. So we can multiply 6 by 4 and you get 24.

Hope it helps! have a great day :)

Answer:

C

Explanation:

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By power transmitted by string, the frequency must be 163.31 Hz.

We need to know about power transmitted to solve this problem. The power transmitted by a  wave on string can be determined by this equation

P = 1/2 . μ . ω² . A² . v

where P is the power, μ is mass per unit length of string, ω is angular speed, A is amplitude and v is wave propagation speed.

the wave propagation can be determined as

v = √(F.l/m)

where F is the string tension, l is length and m is the mass.

From the question above, we know that:

l = 2.7 m

m = 260 g = 0.26 kg

F = 36 N

A = 7.7 mm = 0.0077 m

P = 58 W

Find the mass per unit length

μ = m / l

μ = 0.26 / 2.7

μ = 0.096 kg / m

Find the wave propagation speed

v = √(F.l/m)

v = √(36. 2.7 /0.26)

v = √(373.85)

v = 19.34 m/s

Find the angular speed

P = 1/2 . μ . ω² . A² . v

58 = 1/2 . 0.096 . ω² . 0.0077² . 19.34

ω² = 1053777.29

ω = √1053777.29

ω = 1026.54 rad/s

Find the frequency

ω = 2πf

1026.54 = 2 . 3.14 . f

f = 163.31 Hz

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The answer is 200 joules.

Answer:

Its answer is 200joule.

Explanation:

Hope it's helpful for you

Answer:

The correct answer is 2.51 m/s.

The principle of conservation of momentum states that an isolated system's total momentum will remain unchanged in the absence of an external force. In other words, momentum cannot be created or destroyed but can only be changed by the action of forces as they are described by Newton's laws of motion.

Momentum is the product of an item's mass and its speed, and it is also equivalent to the entire amount of force needed to bring an object to rest.

From the conservation of momentum,

[tex]m_1 u_1 + m_2 u_2 = ( m_1 + m_2 ) v[/tex]

Substitute the values, to get the required speed,

[ ( 0.45 ) ( 0 )] + [ ( 0.67 )([tex]u_2[/tex])] = ( 0.45 + 0.67 ) ( 1.5 )

[tex]u_2[/tex] = 2.51 m/s

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To determine the large dimension, always big dimension should be preferred. Hence, option B is correct.

An area, region, or space's length or width in one direction is referred to as a dimension in mathematics. It merely involves taking an object's length, width, and height into account.

Dimension can be expressed in any one of them, such as Length, Breadth, Width, Height, or Depth.

According to the question, the best possible way to express the dimension in 1.04 m* 4.00 m is because both the dimensions are in the same unit, so it will be easy to calculate the dimension and another thing is that all other dimensions in the option are very small, so it will take more time to measure from them because the desk is large.

Hence, measuring with 1.04 m * 4.00 m will be the more convenient and the best way as well.

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Answer:

I think the correct answer from the choices listed above is option A. The correct arrangement of the substances according to the most to the least ordered particle arrangement should be wood, water and neon gas. Wood should be the first since it is solid which has the most ordered structure as compared to the liquid and a gas. The neon gas is the last since as a gas it has the least ordered structure.

Answer:

A) wood, water, neon gas

Explanation:

wood, water, neon gas.

The particles of solids have an arrangement that is highly ordered and regular. Liquids have an arrangement that is less ordered, and the particle arrangement in gases is the least ordered and regular of the three states of matter.

tell me if im wrong .... hope this helps :)

The height of the point where it hits the ball is 20.171 m.

When a batter hits a ball high in a baseball game,

Time till the ball remains in the air, t = 4.06 seconds.

The acceleration of gravity, g = 9.8 m/s².

The vertex value of time is half of the time, the ball remains in the air

i.e. [tex]\frac{4.06}{2}[/tex] = 2.03 s

Final velocity (v) at the maximum height will be 0

So, According to the First Equation of Motion:

v - u = gt

u = - gt

u = -9.8 × 2.03

u = -19.894 m/s

Now, by using the Second Equation of Motion:

v² - u² = 2gh

Since v = 0

[tex]h = \frac{u^{2} }{2g}[/tex]

h = [tex]\frac{19.894^{2} }{2 * 9.81}[/tex]

h = 20.171 m

The ball will rise 20.171 meter high.

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Justin's average speed for the triathlon is 15.23km/h

Average speed is the total distance covered in total time taken.

(given) 28 minutes to finish the 1500 meter swim

1.75 hours for the 40 kilometer biking portion

70 minutes for the 10 kilometer run

total distance covered = 1500m + 40 km+ 10 km

                                   = 51500m = 51.500km

                                            (1km = 1000m)

total time taken = 28mint + 1.75hr + 70 mint

                           = 203mint

                time in hours = 203/60 hr

                                            (1hour = 60 mint)

average speed = total distance covered / time taken

   = 51.5 x  203/60                    

    = 15.23km/h

Justin's average speed for the triathlon is 15.23km/h

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Answer:

Sound and light are similar in that both are forms of energy that travel in waves.

Explanation:

They both have properties of wavelength, freqency and amplitude. ... Sound can only travel through a medium (substance) while light can travel through empty space. Sound is a form of mechanical energy caused by vibrations of matter.

Answer:

When light moves from one medium (like air) to another medium (like water) it will change directions. This is a "wave-like" behavior and is called refraction. In this way light behaves like other waves such as sound waves. The speed of the light wave also changes when it moves from medium to medium.

Explanation:

Answer:

Smoke alarms detect fires by sensing small particles in the air using a couple of different kinds of technologies. Once they detect those particles above a certain threshold, they signal the alarm to sound so that you and your family can get to safety and call 911. Smoke alarms save lives.

The first one is C!

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Answer:

is there any options

Explanation:

Answer:

for part 1 the answer is 0.303

Explanation:

Answer:

Winter Solstice

Answer:

Three Laws

Newton's Three Laws of Motion. Sir Isaac Newton: The Universal Law of Gravitation. Sir Isaac Newton and the Unification of Physics & Astronomy.

Explanation:

Because most particles fired at metal foil passed straight through, Rutherford concluded that only a small area of an atom is positively charged called the nucleus.

Rutherford's atomic model states that the atom is a small-sized particle that is composed of other fundamental objects i.e. electrons, protons, and neutrons.

In the core of an atom, there is an extremely dense, tiny-sized object called the nucleus which is positively charged.

Moreover, the nucleus is the central point containing all the mass of an atom around which negatively charged particles revolve in circular paths called electrons.

To put it simply, this model suggests that when electrons interacted with atoms in gold metal foil, only a few changed their path after colliding with the massive dense nucleus.

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Answer:

The change in momentum = -20000 kg m/s.

Explanation:

Mass m = 1000 kg

speed v₁ = 20 m/s

speed v₂ = 0 m/s

We know that,

The change in momentum

ΔP = m (Δv)

ΔP = m (v₂ - v₁)

     = 1000 (0 - 20)

     = 1000 (-20)

     = -20000 kg m/s

Thus, the change in momentum = -20000 kg m/s.

Note: negative sign indicates that the velocity is reducing when it hits the barrier.

Answer:

D.) South American becomes dire than normal

Explanation:

La Niña effect can be regarded as an effect that has impacts on the global climate, this effect bring about disruption in normal weather patterns, as a result of this intense storms as well as drought is experienced. The effect could be intense by worsening of above temperature. It bring an increases the probability of having a rainfall below normal. As a result of this

South American becomes dire than normal.

Answer:

4ac (quadruples)

Explanation:

The general formula for centripetal acceleration is given as follows:

[tex]a_{c} = \frac{v^2}{r}\\\\[/tex]   -------------- equation (1)

where,

ac = centripetal acceleration

v = tangential speed

r = radius of circular path

Now, if we double tangential speed, v' = 2v, then the acceleration will become:

[tex]a_{c}' = \frac{(2v)^2}{r}\\\\a_{c}' = \frac{4v^2}{r}[/tex]

using equation (1):

[tex]a_{c}' = 4a_{c}[/tex]

therefore, the correct answer is:

4ac (quadruples)

Answer:

Uniform rectilinear movement (m. r. u.)

Explanation:

It is a continuous movement without acceleration, that is, it moves at a constant speed. The speed does not change over time, for this reason, there is no change in acceleration.

Vf = final velocity = 50/30 [km/s] = 1.67 [km/s]

Vo = initial velocity = 50/30 [km/s] = 1.67 [km/s]

Answer:

Explanation:

The correct option of the given question will be option © that is frequency changes.

According to the Doppler Effect, when source is moving towards the observer then the frequency increases and when the source is moving away from the observer then the frequency decreases, but the magnitude of the amplitude in both the cases will remain same. Whereas the speed of sound waves will remain constant as it was earlier. According to this effect, when there is a relative motion between the source and the observer then there will be the change in the frequency.

So, the correct answer will be that the frequency changes.

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Answer:

nah bro tesla

Explanation:

Answer:

jaja I don't remember it's been 6 years ago u don't remember nothing of that

Answer:

[tex]4800\; {\rm kg}[/tex].

Explanation:

When an object of mass [tex]m[/tex] travels at a velocity of [tex]v[/tex], the momentum [tex]p[/tex] of that object would be [tex]p = m\, v[/tex].

Momentum is conserved immediately after the collision. Hence, the momentum that the [tex]3600\; {\rm kg}[/tex] vehicle lost in the collision would be equal to the momentum that the other vehicle has gained.

Momentum that the [tex]3600\; {\rm kg}[/tex] vehicle lost:

[tex]\begin{aligned}(\text{momentum change}) &= (\text{new momentum}) - (\text{original momentum}) \\ &= m\, v(\text{new}) - m\, v(\text{old}) \\ &= m\, (v(\text{new}) - v(\text{old})) \\ &= 3600\; {\rm kg} \, (9.0\; {\rm m\cdot s^{-1}} - 21.0\; {\rm m\cdot s^{-1}}) \\ &= (-43200)\; {\rm kg \cdot m \cdot s^{-1}}\end{aligned}[/tex].

The vehicle that was originally at rest would have gained that [tex]43200\; {\rm kg \cdot m\cdot s^{-1}}[/tex] of momentum. The momentum of that vehicle was [tex]0\; {\rm kg \cdot m \cdot s^{-1}}[/tex] before the collision since that vehicle was initially not moving. After gaining the [tex]43200\; {\rm kg \cdot m\cdot s^{-1}}\![/tex] of momentum, the new momentum of that vehicle would be [tex]p = 43200\; {\rm kg \cdot m\cdot s^{-1}}\!\![/tex].

Rearrange the equation [tex]p = m\, v[/tex] to obtain an expression for mass: [tex]m = (p / v)[/tex]. It is given that the velocity of this vehicle is [tex]v = 9.0\; {\rm m\cdot s^{-1}}[/tex] after the collision. Substitute both momentum [tex]p[/tex] and velocity [tex]v[/tex] into the equation [tex]m = (p / v)\![/tex] to find mass [tex]m\![/tex]:

[tex]\begin{aligned} p &= \frac{m}{v} \\ &= \frac{43200\; {\rm kg \cdot m \cdot s^{-1}}}{9.0\; {\rm m\cdot s^{-1}}} \\ &= 4800\; {\rm kg} \end{aligned}[/tex].

In other words, the mass of the vehicle that was originally not moving would be [tex]4800\; {\rm kg}[/tex].

If a bird flew from my house to the sandwich shop in a straight line, it would travel a distance of 10.44 miles.

The direction that it  should  fly from my house to get to the shop is at an angle 73.30°.

Pythagorean theorem-

The position vector are

OA = -6j AB = -10iBC=3j

where

O is the position of the house

C is the position of the shop.

Now drawing a perpendicular from C to OA at P we have,

Thus we have,

PC = 10i

PA = 3j

Thus,

OP = OA - PA = -6j + 3j = -3j

OC is the resultant of CP and OP

a) Thus the magnitude of OC

| OC | = √CP^2 + OP^2

= √ (10^2 +3^2) =10.44

b) The angle made by OC with OP

tan θ = OP/CP = 10/3

θ = 73.30°

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Answer:

the app your on now is great and can ask anything