if vector A=2i+3j-k and vector B=4i+6j-2k. The angle between them will be: a) 0°b)45°c)90°d)60°​

Answer:

2.5 ms^-2

Explanation:

acceleration

= (final velocity - initial velocity)/time

= [(40m/s) - (20m/s)]/8s

= (20m/s)/8s

= 5/2 m/s²

= 2.5 m/s²

= 2.5 ms^-2

Answer:

1st question c part

2nd question c part

Answer:

Answer5 mExplanation:when u draw this on paper u will find that it is forming a right angle

triangle. therefore, using Pythagoras

theoremdisplacement

Light waves are electromagnetic waves while sound waves are mechanical waves. Light waves are transverse while sound waves are longitudinal. Light waves can travel in vacuum. Sound waves require a material medium to travel, and hence, cannot travel in vacuum.

They make use of radio waves. Radio waves signal are sent their headsets that in turn translates the signal in the form of sound. While communicating with people on Earth – the radio waves are transmitted which in turn are transformed to sound wave by a radio set. Radio waves comes from the light spectrum called Electromagnetic Spectrum and thus they are light waves. Unlike sound, light waves doesn’t need a medium to travel and it is for this reason that the sun ray travels through space to the Earth

We all know who was the first man that landed on moon? But were the first words ever heard in space?

It was the announcement of landing that was said by Neil Armstrong: “Lunar Module has landed on moon”

Answer: Light waves are electromagnetic waves while sound waves are mechanical waves. Light waves are transverse while sound waves are longitudinal. Light waves can travel in vacuum. Sound waves require a material medium to travel, and hence, cannot travel in vacuum.

Explanation:

Answer:

The pressure at the bottom of the river is less than that at the bottom of the lake.

Explanation:

From Bernoulli's equation, the pressure difference is given by

ΔP = ρgΔh + ρ(v₂² - v₁²)/2 where ρ = density of water, g = acceleration due to gravity, Δh = depth, v₁ = velocity at top, v₂ = velocity at bottom

For the lake, v₁ = v₂, since the velocity at the top and bottom are the same. So,

ΔP₁ = ρgΔh + ρ(v₁² - v₁²)/2 = ρgΔh + 0 = ρgΔh

P₂ - P₁ = ρgΔh

P₂ = P₁ + ρgΔh

For the river, v₁ < v₂, since the velocity at the top of the river is greater than at the bottom.

So,

ΔP₂ = ρgΔh + ρ(v₂² - v₁²)/2.

Since  v₁ < v₂, ρ(v₂² - v₁²)/2 will be negative,

So,

ΔP₂ = ρgΔh - ρ(v₂² - v₁²)/2.

Since ρ(v₂² - v₁²)/2 is negative, making ΔP less than that in the lake.

So, ΔP₂ = ΔP₁ -  ρ(v₂² - v₁²)/2.

ΔP₂ = P₃ - P₁

P₃ - P₁ = P₂ - P₁ -  ρ(v₂² - v₁²)/2.

P₃ = P₂ - ρ(v₂² - v₁²)/2.

where P₃ = pressure at bottom of the river and P₂ = pressure at bottom of the lake and P₁ = atmospheric pressure at top of river and lake respectively.

Since the factor ρ(v₂² - v₁²)/2 is removed from the pressure at the bottom of the lake, the pressure at the bottom of the river is therefore less than that at the bottom of the lake.

Explanation:

Assuming the suitcase is near the surface of the earth, g = 9.8 m/s².

F = ma

F = (20 kg) (9.8 m/s²)

F = 196 N

Answer:

B.

Explanation:

as there is a '-' sign before the magnification value, it forms a real image.

so the last two options get cancelled.

as the value of magnification is 0.87 ie. lesser than 1, we can say that the image is smaller.

The type of image is formed by a lens if m = -0.87 would be smaller than the object and the object is real

A lens is a transmissive optical tool that employs refraction to focus or disperse a light beam. The power of the lens is expressed in the dioptre which is the reciprocal of the focal length of the lens.

The image formation through the lens is calculated with the help of the lens formula given as follows

1/f = 1/v - 1/u

where f is the focal length of the lens

u is the distance of the object from the lens

v is the distance of the image formed from the

magnification (m) = size of image /size of the object

As given in the problem image is formed by a lens if m = -0.87

Thus, the negative sign represents that the image formed by the object is real, and the magnitude of the magnification is less than 1 this represents that size of the image is smaller than the size of the object.

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Answer:

the lens is located in the eye. by changing its shape, the lens changes the focal distance of the eye. in other words,it focuses the light rays that pass through it (and onto the retina) in order to create clear images of objects that are positioned

at various distances.

Explanation:

Given that,

Number of loops are 3

Length of slinky is 3.75 m

They time 20 oscillations in  6.73 s.

We need to find the wavelength of  the standing wave.

For 3 loops, [tex]L=\dfrac{3\lambda}{2}[/tex]

Here, [tex]\lambda[/tex] is the wavelength of the standing wave

So,

[tex]\lambda=\dfrac{2L}{3}\\\\\lambda=\dfrac{2\times 3.75}{3}\\\\\lambda=2.5\ m[/tex]

So, the wavelength of the standing wave is 2.5 m.

Answer:

The volume of the cylinder is [tex]653.71\ \text{cm}^3[/tex]

Explanation:

Given that,

The height of the cylinder is 13 cm

Radius of the cylinder is 4 cm

We need to find the volume of the cylinder. The formula that is used to find the volume of a cylinder is given by :

[tex]V=\pi r^2 h\\\\V=\dfrac{22}{7} \times (4)^2 \times 13\\\\V=653.71\ \text{cm}^3[/tex]

So, the volume of the cylinder is [tex]653.71\ \text{cm}^3[/tex]

Answer:

653.45 is the answer

Explanation:

Answer:

PFA

:-)

Explanation:

Answer:

Which best describes what happens if two waves meet and build on each other?

destructive interference

reflection

absorption

Explanation:

When two waves meet in phase they will overlap together and form a constructive interference. The resultant amplitude of the waves will be greater than that of individual waves.

A wave of greater, lower, or the same amplitude is created when two waves merge through interference by combining their displacements at all points in space and time.

The interaction of waves that are coherent or correlated with one another, either because they originate from the same source or because their frequencies are similar or almost identical, leads to both constructive and destructive interference.

All sorts of waves, including light, radio, acoustic, surface water waves, gravity waves, and matter waves, can exhibit interference effects. In constructive interference, the waves are in single phase forms a resultant wave with higher amplitude.

When waves from out of phase meets, the resultant wave will have an amplitude less than the individual amplitudes. Here, the waves are meet in phase and build on each is constructive interference.

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Answer:

Explanation:

i )

When it is disconnected with the battery , the charge stored in it becomes fixed . When the plate distance becomes half , its capacitance becomes twice from C to 2C . Let charge stored in it at the time of disconnection from battery be Q . Let plate separation reduces from d to d / 2

So charged stored in it will remain unchanged .

ii )

Potential difference = charge / capacitance

in the first case potential difference = Q / C

in the second case potential difference = Q / 2C

So potential difference becomes half .

iii ) electric field = potential diff / plate separation

in the first case electric field = Q / (d x C )

in the second case electric field = 2 Q / (d x 2C)

= Q / (d  x C )

So electric field remains unchanged .

iv)

energy stored in first case = Q² / 2C

In the second case energy stored = Q² / 2x2C

so energy stored becomes half .

Answer:

The word ‘radiation’ is used to describe particles or waves that are emitted by an object  

In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium. This includes: electromagnetic radiation, such as radio waves, microwaves, infrared, visible light, ultraviolet, x-rays, and gamma radiation (γ)

Explanation:

There are four major types of radiation: alpha, beta, neutrons, and electromagnetic waves such as gamma rays. They differ in mass, energy and how deeply they penetrate people and objects.

The first is an alpha particle. These particles consist of two protons and two neutrons and are the heaviest type of radiation particle. Many of the naturally occurring radioactive materials in the earth, like uranium and thorium, emit alpha particles

The second kind of radiation is a beta particle. It's an electron that is not attached to an atom. It has a small mass and a negative charge. Tritium, which is produced by cosmic radiation in the atmosphere and exists all around us, emits beta radiation. Carbon-14, used in carbon-dating of fossils and other artifacts, also emits beta particles. Carbon-dating simply makes use of the fact that carbon-14 is radioactive. If you measure the beta particles, it tells you how much carbon-14 is left in the fossil, which allows you to calculate how long ago the organism was alive.

The third is a neutron. This is a particle that doesn't have any charge and is present in the nucleus of an atom. Neutrons are commonly seen when uranium atoms split, or fission, in a nuclear reactor. If it wasn't for the neutrons, you wouldn't be able to sustain the nuclear reaction used to generate power.

The last kind of radiation is electromagnetic radiation, like X-rays and gamma rays. They are probably the most familiar type of radiation because they are used widely in medical treatments. These rays are like sunlight, except they have more energy. Unlike the other kinds of radiation, there is no mass or charge. The amount of energy can range from very low, like in dental x-rays, to the very high levels seen in irradiators used to sterilize medical equipment.

Answer:

gagaggagagagagooo

Explanation:

gagagagagagagagaoooo

Answer:

The answer  is The acceleration is double its original value.

Explanation:

Hope this helps....

Have a nice day!!!!

Answer:

The acceleration is half of its original value

Explanation:

Answer:

The MKS (metre, kilogram, second) system of units is the fundamental core of the SI (Systeme Internationale, or International System) of measurement. As various fields grow new forms of measurements based on MKS, terms or exact definitions may vary in different scientific or engineering disciplines. These inconsistencies are sorted out by the international committee that defines the SI system of units and keeps it up to date.

So the MKS is the static core, and the SI is the evolving, growing system of metric measurement.

Metres and kilograms were introduced after the French Revolution around 1790. Seconds were added by the 1830s, building the MKS system. More units came later. By 1948, a need was seen to develop a clear and consistent set of terms for measurement, and this led to 12 years of work, ending with the release of the first version of the SI in 1960.

The SI now has seven base units of measure. It begins with the original three metre, kilogram, and second, and adds the ampere for electricity, candela for light, kelvin for temperature, and mole for amount (number of atoms or molecules) of a substance.

The SI defines how each fundamental unit can be measured or obtained experimentally. These definitions have changed over time. For example, the metre was originally a measure related to the circumference of the Earth, then a set number of waves of a particular wavelength, and now a distance traveled by light in a vacuum in a certain period of time.

The SI also defines modifying terms such as milli-, centi-, and kilo- that are a specific number of each unit.

The SI includes many other derived units, as well.

By standardizing international use of measurements across different fields of science and engineering, the SI reduces confusion that would slow scientific progress and error that can produce engineering catastrophe such as the loss of the Mars Climate Orbiter in 1999 due to a table that should have been in metric units (kilograms and meters) being provided in United States customary units (pounds and inches).*

The Mars Climate Orbiter and its mission were lost due to a failure to use SI units consistently.

Hope this help you!:)

Answer:

True

Explanation:

The average kinetic energy is the measure of how freely the molecules of a substance moves relative to the other molecules within the substance. Gas and liquids are together termed fluids,  but the molecules of a gas naturally has more more average kinetic energy that that of a liquid, if they are kept at the same temperature. This explains why gases are easy to expand, and have to be confined by a container. So the particles of a gas has more kinetic energy that that of a liquid even if they are kept at the same temperature.

It isn't best to wear loose fitting clothing when exercising, as you may not feel too comfortable. It depends on the person. However there are a few advantages.

• Tight clothing may not be comfortable as well

• Looser clothing allows easy evaporation of sweat

Then again when it says " loose - fitting " it may mean not too baggy. Baggy clothing can have an impact on your physical activity.

Answer All of the above

For people on a p e x

Answer:

T= 2.66 seconds

Explanation:

Convert 80 km to m, which would be 0.08 m

[tex]t = d \div s[/tex]

[tex]t = 0.08 km\div 108kmph[/tex]

[tex]t = 0.00074074074 \: h[/tex]

[tex]1 \: hour = 3600 \: sec[/tex]

[tex] \frac{1}{3600} \times \frac{0.00074}{x} [/tex]

[tex]0.00074074074h \times 3600s = 2.66s[/tex]

Answer:

  #_total = 4.38 10⁹ liter

Explanation:

For this exercise we can use a direct proportion rule (rule of three). If 4 people use 1200 liters how much water 1 person consumes

            #_water = 1 person (1200 liter / 4 person)

            #water = 300 liters

Now we look for the consumption of this person in a year, if 1 person consumes 300 liters 1 day, how many liters they consume in a year (365 days)

           #_water_person_total = 365 days (300 liters / 1 day)

           #_water_person_total = 109500 liters

This is the water consumption of 1 person in a year, the total of 40000 people how much they consume

           #_total = 40000 person (109500 liter / 1 person)

           #_total = 4.38 10⁹ liter

El término deporte engloba diversas formas de ejercicio, juegos y competiciones, que en su mayoría se relacionan con la actividad física de las personas. Así, los deportes más populares a nivel mundial son el fútbol, el baloncesto, el tenis, el rugby, etc.

Todos estos deportes, sin importar sus características, requieren de sus deportistas una serie de normas de conducta que hacen que los mismos sean cada vez mejores en sus respectivos deportes. Estas son, fundamentalmente, un buen entrenamiento, una correcta alimentación, un suficiente descanso y un seguimiento de las reglas del deporte.

La falta de alguna de estas 4 normas de conducta hace que el atleta no maximice su rendimiento, influyendo en forma negativa en sus resultados competitivos.

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Explanation:

Newton's first law states that if a body is at rest or moving at a constant speed in a straight line, it will remain at rest or keep moving in a straight line at constant speed unless it is acted upon by a force.

Example a ball at rest remains at rest unless a net force is act on it. If u kick that ball, net force will act on it

This is why we called motion of inertia

Answer:

(B)

Explanation:

the boy will fall away from the bus if the bus is moving.

Answer:

[tex]\huge\boxed{Divide\ distance \ by \ time}[/tex]

Explanation:

Speed = Distance / Time

So, to find distance, we actually divide distance by rime.

Answer:

[tex]\large \boxed{\mathrm{divide \ distance \ by \ time}}[/tex]

Explanation:

Using the formula to calculate speed:

[tex]\displaystyle \sf speed =\frac{distance}{time}[/tex]

We divide the distance by the time taken to get the average speed.

Answer:

7.2 seconds

Explanation:

50=5

72=t, criss-cross, t=72 (5)/50

Answer:

17) a) 30 kg·m/s

b) 30 kg·m/s

c) 0.3 m/s.

18) 2.4 m/s

19) 360,000 N

The different make of  car is safer because the force acting on it  is 28,800 N, resulting much less impact

Explanation:

17) By conservation of linear momentum principle, we have;

m₁·v₁ + m₂·v₂ = m₁·v₁' + m₂·v₂'

Where;

m₁ = The mass of the astronaut = 100 kg

v₁ = The initial velocity of the astronaut = 0 m/s

m₂ = The mass of the equipment box = 2.5 kg

v₂ = The initial velocity of the equipment box = 0 m/s

v₁' = The final velocity of the astronaut

v₂' = The final velocity of the equipment box = 12 m/s

The final momentum of the equipment box = Mass of the equipment box × Final velocity

a) The final momentum of the equipment box = 2.5 kg × 12 m/s = 30 kg·m/s

b) Given that the box and the astronaut will move in opposite directions, we have;

m₁·0 + m₂·0 = -m₁·v₁' + m₂·v₂'

m₁·v₁' = m₂·v₂'

Therefore, the momentum of the astronaut will be equal to the momentum of the equipment box = 30 kg·m/s

c)  The velocity of the astronaut is given by th following relation;

100×0 + 2.5×0 = -100×v₁' + 2.5×12

100×v₁' = 2.5×12

v₁' = 2.5×12/100 = 30/100 = 0.3 m/s

The final velocity of the astronaut = 0.3 m/s.

18) By conservation of linear momentum principle, we have;

m₁·v₁ + m₂·v₂ = m₁·v₁' + m₂·v₂'

Where;

m₁ = The mass of the railway truck= 4000 kg

v₁ = The initial velocity of the railway truck= 8 m/s

m₂ = The mass of the stationary truck = 6000 kg

v₂ = The initial velocity of the stationary truck = 0 m/s

v₁' = The velocity of the two trucks immediately after collision

Therefore, we have;

4000 kg × 6 m/s + 6000 × 0 = (6000 + 4000) × v₁' = 10,000·v₁'

24,000 kg·m/s = 10,000·v₁'

v₁' = 24,000/10,000 = 2.4 m/s

The velocity of the two trucks immediately after collision is = 2.4 m/s

19) The change in kinetic energy of the car due to the collision = 1/2·m·(v₂² - v₁²)

The initial velocity of the car, v₁ = 12 m/s

The final velocity, v₂ = 0 m/s

The mass of the car, m= 600 kg

The time in which the car is brought to rest = 2 seconds

Initial time at point of collision, t₁ = 0 s

Time after collision, t₂ = 0.02 s

By Newton's second law of motion, we have

The force F acting on the car = Rate of change in momentum produced by the force

F = m × dv/dt

Force  = m × (v₂ - v₁)/(t₂ - t₁) = 600×(0-12)/(0.02 - 0) = -360,000 kg·m/s²

The force acting on the car  is equal and opposite to the force of the car =  360,000 N

b) For the different make of the car, we have;

m × (v₂ - v₁)/(t₂ - t₁) = 600×(0-12)/(0.25 - 0) = -28,800 kg·m/s². = -28,800 N

Therefore, the different make of  car is safer because the force acting on it  is 28,800 N, resulting much less impact.

Answer:

Mass and distance

Explanation:

The force of gravity the masses exert on each other. If one of the masses is doubled, the force of gravity between the objects is doubled. increases, the force of gravity decreases. Hence, answer is mass and distance