calculate the force exerted by a mental ball having a mass of 70kg moving with speed of 20m/s>2
​

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.

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Answer:

gagaggagagagagooo

Explanation:

gagagagagagagagaoooo

Answer:

2660 m

Explanation:

Sum of the forces in the first 6.00 s:

∑F = ma

F − mg = ma

35.0 N − (0.800 kg) (10 m/s²) = (0.800 kg) a

a = 33.75 m/s²

The height it reaches during this time is:

Δy = v₀ t + ½ at²

Δy = (0 m/s) (6.00 s) + ½ (33.75 m/s²) (6.00 s)²

Δy = 607.5 m

The velocity it reaches is:

v = at + v₀

v = (33.75 m/s²) (6.00 s) + 0 m/s

v = 202.5 m/s

After the battery runs out, the drone is in free fall.  At the highest point, the velocity is 0.  The height at this point is:

v² = v₀² + 2aΔy

(0 m/s)² = (202.5 m/s)² + 2 (-10 m/s²) (h − 607.5)

h ≈ 2660 m

a) Her acceleration during the slide is -6.67 m/s².

b) She slides 1.03 seconds until she stops.

a) We can find her acceleration during the slide with Newton's second law:

[tex] F = ma [/tex]                        

Where:

F: is the force    

m: is the mass = 92.45 kg

a: is the acceleration =?

The force acting on the baseball player is equal to the friction force ([tex]F_{\mu}[/tex]), and it is negative because it is in the opposite direction to the motion:

[tex] -\mu N = ma [/tex]

[tex] -\mu mg = ma [/tex]

[tex] a = -\mu g [/tex]

Where:

N: is the normal force = mg

μ: is the coefficient of kinetic firction = 0.68

g: is the acceleration due to gravity = 9.81 m/s²

Hence, her acceleration during the slide is:

[tex] a = -0.68*9.81 m/s^{2} = -6.67 m/s^{2} [/tex]

b) We can calculate how long does she slide until she stops with the following kinematic equation:

[tex] v_{f} = v_{0} + at [/tex]

Where:

[tex] v_{f} [/tex]: is the final speed = 0 (when she stops)

[tex] v_{0} [/tex]: is the initial speed = 6.87 m/s

t: is the time =?

Then, the time is:

[tex] t = -\frac{v_{0}}{a} = -\frac{6.87 m/s}{-6.67 m/s^{2}} = 1.03 s [/tex]

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Explanation:

The area under a displacement vs time graph is the absement.

6. Force

7 speed

8 distance

9 acceleration

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:

0 degrees Celsius is 273 degrees Kelvin. As both pressure and volume are proportional to absolute temperature, in order to double both you would need to quadruple the temperature. I.e. 273 X 4 = 1092 Kelvin = 819 Celsius

Explanation:

Ramsar has the highest level of natural radiation in the world.

Hot springs located in the Arkaroola Wilderness Sanctuary in Southern Australia are also credited with higher than normal radiation levels, due to spring water coming in contact with rocks rich in uranium and radon.

Answer:

Explanation:

The velocity ratio of  a wheel and axle is the ratio of the radius (R) of the wheel to the radius (r) of the axle. It is expressed as;

VR = R/r

Since radius = diameter/2

VR = (D/2)/(d/2)

VR = D/d

D is the diameter of the wheel and 'd' is the diameter of the axle.

Given VR = 3 and d = 5cm

3 = D/5

D = 15 cm

If the diameter of the wheel is 15cm, the radius of the wheel will be 15/2 = 7.5cm.

b) Workdone by the load = Load * distance moved by load

Given load = 60kg

Distance moved by load = 2π*radius of axle

Distance moved by load  = 2π(0.025) = 0.157

workdone by load = 60* 0.157 = 9.42J

Effort = Workdone by load/distance moved by the wheel

Effort = 9.42/2π(0.075)

Effort = 9.42/0.471

Effort = 20kg

Hence the effort applied is 20kg

c) MA = Load/Effort

MA = 60/20

MA = 3

d) Efficiency = MA/VR * 100%

Efficiency = 3/3 * 100%

Efficiency = 100%

Answer:

Explanation:

Energy of gamma ray = 2.2233 MeV

Let mass of neutron be n  amu  

mass defect of deuteron = 2.013553212 - ( 1.007 276 467 + n ) u .

in terms of energy this mass defect will be equal to energy of gamma ray

1 amu = 931 MeV

931 [ 2.013553212 - ( 1.007 276 467 + n ) ] =  2.2233

( 1.007 276 467 + n ) -  2.013553212  = .00238807733

n = 1.008664822 amu

so mass of neutron = 1.008664822 amu

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 percentage error in quantity P is 19%.

Explanation:

It is given that,

A physical quantity P is related to four observables a, b and c as follows:

[tex]P=\dfrac{a^3b^2}{c^4}[/tex]

The percentage errors of measurements in a, b and c are 1%, 4% and 2% respectively.

We need to find the percentage error in quantity P. It is given by :

[tex]\dfrac{\Delta P}{P}\times 100=(3\times \dfrac{\Delta a}{a}+2\times \dfrac{\Delta b}{b}+4\times \dfrac{\Delta c}{c})\\\\=3\times 1+2\times 4+4\times 2\\\\\dfrac{\Delta P}{P}\times 100=19\%[/tex]

So, the percentage error in quantity P is 19%.

Answer:

[tex]t = 0.75 \ hr = 0.75 *60 = 45 \ minutes[/tex]

Explanation:

From the question we are told that

   The  hydraulic conductivity is  [tex]Ks = 10\ mm/hr[/tex]

    The  effective matrix potential [tex]Ns = 20 \ mm[/tex]

    The  intensity of  rainfall is  [tex]I = 30 \ mm/hr[/tex]

    The runoff rate [tex]R = 15 \ mm/hr[/tex]

Generally the run off rate is mathematically represented as  

      [tex]R = (I - Ks) t[/tex]

Here t is the amount of runoff generated

=>   [tex]15 = (30 - 10) t[/tex]

=>  [tex]t = 0.75 \ hr[/tex]

converting to minutes

    [tex]t = 0.75 \ hr = 0.75 *60 = 45 \ minutes[/tex]

Answer:

PFA

:-)

Explanation:

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:

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 .

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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Answer:

When we have irregular objects, it may become very hard to calculate the volume of the object, as we actually can not use any simple equation to find it.

The mass is less tricky, just find a scale and wheight it, now we know the mass of the irregular object.

One way to measure the volume of the object is using water... how we do it?

Get some recipient with water, measure the height of the water.

Introduce your object into the water and totally submerge it, now the level of the water will rise. This is because as you introduce the object under the water, you are displacing up a given volume of water that has the same volume as the irregular object.

Now that you know the height of the water before and after you put your object, you can easily calculate the volume of water displaced, and that will be the volume of the object (the tricky part may be totally submerging the object if, for example, is wood and it floats, here you can use a thin wire to push it down but it will affect a little bit the measures.)

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:

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.

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.

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:

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

triangle. therefore, using Pythagoras

theoremdisplacement

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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Explanation:

Let 'F' be force acting perpendicularly, 'A' be the area and 'P' be the pressure exerted.

Then,

Pressure is directly proportional to the the force acting perpendicularly i.e.

P ∝ F ............. (i)

Pressure is inversely proportional to the area on which force acts i.e.

P ∝ 1/A ........... (ii)

Combining equations (i) and (ii),

P ∝ F/A

or, P = K × F/A [where K is a constant]

If F is 1N, A is 1m² and P is 1 N/m², then K is 1.

So, P = F/A proved...

Answer:

(B)

Explanation:

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

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

In free fall

[tex]\boxed{\sf s=-\dfrac{1}{2}gt^2}[/tex]

[tex]\\ \sf\longmapsto s=-\dfrac{1}{2}\times 9.8(1)^2[/tex]

[tex]\\ \sf\longmapsto s=-4.9(1)[/tex]

[tex]\\ \sf\longmapsto s=-4.9m[/tex]

[tex]\\ \sf\longmapsto s=4.9m[/tex]