A 1000 kg car crashed into a barrier. The car changed speed from 30 m/s to 20 m/s in 0.2 seconds. What force did the barrier apply to stop the car?

Answer

I feel the answer is C because it could cause mental and physical trauma

Explanation:

Answer:

which of the following statements BEST describes the difference between an atom and an ion ?

Answer:

well the correct answer is

Explanation:

A charged atom is known as an ion, well it can be negative as well as positive charge.

A mechanical wave is a disturbance in matter that transfers energy through the matter. The matter through which a mechanical wave travels is called the medium

or media in plural.

Mechanical wave are waves that travels through a medium or matter.

A wave is a disturbance that travels or propagates from the place where it was created.

Waves transfer energy from one place to another, but they do not necessarily transfer any mass.

There are two types of waves;

mechanical wave and electromagnetic waves

electromagnetic waves are waves that that do not need any means of medium for propagation.

Examples of electromagnetic wave includes; light wave , radio wave e.t.c

Mechanical waves are waves that need medium for propagation. Example of mechanical waves includes ; sound wave , water wave e.t.c

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Answer:

Distance and time.

Explanation:

Speed=Distance/time

The two factors which we need in order to calculate the speed of an object are the distance covered by the object and the time taken to cover that distance.

Speed is the rate of change of position of an object in any direction. Speed is a scalar quantity as it has only magnitude and no direction. It is measured as the ratio of the distance covered by an object to the time taken in which the distance was covered by that object.

Speed has the dimension of distance covered by the time taken. Thus, the SI unit of speed is the combination of the basic units of distance and the basic unit of Time. Thus, the SI unit of speed is meter per second (m/s).

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Answer:

5 newtons

Explanation:

Just divide them

Answer:

3 hrs

Explanation:

the distance covered by victor= 210 km

speed= 70 km/hrs

so, 70×3= 210

so the answer is 3 hrs

BTW im a small kid so don't just right away say the explanation sucks and the subject physics is not yet started in my grade.

edit: don't give me brainless answer plz.

Answer:

Explanation:

F = m*a = (0.5)*15 = 7.5 N

Answer:

The current value of the Hubble's constant = 73 km/sec/Mpc.

t = 71.9 trillion years will be the new age of universe if the Hubble constant = 700 km/s/Mpc

Explanation:

The current value of the Hubble's constant = 73 km/sec/Mpc. However, recent discoveries in the cosmology contradicts the idea of Hubble constant as being fixed. Some scientists are not agreeing on this value and the debate is going on.

Hubble law states that how fast universe is expanding or in other words, galaxies are expanding separating with a speed directly proportional to the distance of galaxies to the earth.

Hence,

v is directly proportional to d

where, v = apparent velocity

d = distance

if we equate velocity and distance then there comes Hubble constant.

v = [tex]H_{0}[/tex] x d

 [tex]H_{0}[/tex] = 73 km/sec/Mpc

where, Mpc = Mega Parsec = 1 Mpc = 3.086 x [tex]10^{19}[/tex] km      

We can use Hubble constant to tell the age of universe.

t = d/v

t = d/( [tex]H_{0}[/tex] xd)

t = 1/[tex]H_{0}[/tex]

Scientist calculated the age of universe by using Hubble constant, which is 13.4 billion years.

Now, if we hypothetically change the value of Hubble constant,

from [tex]H_{0}[/tex] = 73 km/sec/Mpc to [tex]H_{0}[/tex] = 700 km/sec/Mpc

then the age of universe will be:

t = 1/[tex]H_{0}[/tex]

first convert the units of new [tex]H_{0}[/tex] into 1/s

[tex]H_{0}[/tex] = (700) x (/3.08 x [tex]10^{19}[/tex] )

[tex]H_{0}[/tex] = 227.27 x[tex]10^{-19}[/tex]  = 2.27 x [tex]10^{-21}[/tex] 1/s

So,

Age of universe will be:

t = 1/[tex]H_{0}[/tex] = 1/2.27x[tex]10^{-21}[/tex] 1/s

t = 2.27 x [tex]10^{21}[/tex] s

t = 71.9 trillion years

t = 71.9 trillion years will be the new age of universe if the Hubble constant = 700 km/s/Mpc

Given value:

Hubble Constant,

We know,

By substituting the value of "Mpc" in Hubble constant, we get

→ [tex]H_o = \frac{700}{3.086\times 10^{19}}[/tex]

        [tex]= 227\times 10^{-19} \ 1/s[/tex]

        [tex]= 2.27\times 10^{-21} \ 1/s[/tex]

The Hubble's time will be:

→ [tex]H_o = \frac{1}{t}[/tex]

or,

→ [tex]t = \frac{1}{H_o}[/tex]

     [tex]= \frac{1}{2.27\times 10^{-21}}[/tex]

     [tex]= 4.4\times 10^{20} \ seconds[/tex]

Thus the above approach is right.

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Answer:

See the answers below.

Explanation:

In order to solve this problem we must use the principle of energy conservation. Which tells us that the energy of a body will always be the same regardless of where it is located. For this case we have two points, point A and point B. Point A is located at the top at 120 [m] and point B is in the middle of the cliff at 60 [m].

[tex]E_{A}=E_{B}[/tex]

The important thing about this problem is to identify the types of energy at each point. Let's take the reference level of potential energy at a height of zero meters. That is, at this point the potential energy is zero.

So at point A we have potential energy and since a velocity of 18 [m/s] is printed, we additionally have kinetic energy.

[tex]E_{A}=E_{pot}+E_{kin}\\E_{A}=m*g*h+\frac{1}{2}*m*v^{2}[/tex]

At Point B the rock is still moving downward, therefore we have kinetic energy and since it is 60 [m] with respect to the reference level we have potential energy.

[tex]E_{B}=m*g*h+\frac{1}{2}*m*v^{2}[/tex]

Therefore we will have the following equation:

[tex](6.5*9.81*120)+(0.5*6.5*18^{2} )=(6.5*9.81*60)+(0.5*6.5*v_{B}^{2} )\\3.25*v_{B}^{2} =4878.9\\v_{B}=\sqrt{1501.2}\\v_{B}=38.75[m/s][/tex]

The kinetic energy can be easily calculated by means of the kinetic energy equation.

[tex]KE_{B}=\frac{1}{2} *m*v_{B}^{2}\\KE_{B}=0.5*6.5*(38.75)^{2}\\KE_{B}=4878.9[J][/tex]

In order to calculate the velocity at the bottom of the cliff where the reference level of potential energy (potential energy equal to zero) is located, we must pose the same equation, with the exception that at the new point there is only kinetic energy.

[tex]E_{A}=E_{C}\\6.5*9.81*120+(0.5*9.81*18^{2} )=0.5*6.5*v_{C}^{2} \\v_{c}^{2} =\sqrt{2843.39}\\v_{c}=53.32[m/s][/tex]

Answer:

v= 17.15 m/s

Explanation:

mass of the book=0.1 Kg

height above ground, h= 15 m

Using conservation of energy

Potential energy is converted into kinetic energy

[tex]mgh = \frac{1}{2}mv^2[/tex]

[tex]v=\sqrt{2gh}[/tex]

[tex]v=\sqrt{2\times 9.8\times 15}[/tex]

[tex]v=\sqrt{294}[/tex]

v= 17.15 m/s

Hence, the book will hit the ground at the speed of 17.15 m/s.

The satellite is moved to a new circular orbit that is 2R from the center of the moon, then the gravitational field strength of the moon at this new distance would be one-fourth of the initial gravitational field.

It can be defined as the force by which a body attracts another body toward its center as the result of the gravitational pull of one body and another.

As given in the problem A satellite of mass m orbits a moon of mass M in a uniform circular motion with a constant tangential speed of v. The gravitational field strength at a distance R from the center of the moon is gR. The satellite is moved to a new circular orbit that is 2R from the center of the moon.

The gravitational field strength is inversely proportional to the square of the distance from the center of the planet.

Thus, the gravitational field strength of the moon at this new distance would be one-fourth of the initial gravitational field.

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Answer:

The weight of the combined system is 1989.8 N.

Explanation:

The weight, W, of an object can be expressed as;

W = mg

where m is the mass of the object, and g is the acceleration due to gravity.

Weight of the combined system = weight of tank + weight of water

mass of the plastic tank = 3 kg

weight of the plastic tank = m x g

                               = 3 x 9.8

                               = 29.4 N

Weight of the plastic tank is 29.4 N

But,

density = [tex]\frac{mass}{volume}[/tex]

mass = density x volume

volume of water = 0.2 [tex]m^{3}[/tex], density of water = 1000 kg/[tex]m^{3}[/tex].

mass  = 1000 x 0.2

         = 200

mass of water = 200 kg

weight of water = 200 x 9.8

                   = 1960 N

Thus,

combined weight of the system = 29.4 + 1960

                        = 1989.8 N

The weight of the combined system is 1989.8 N.

Answer:

1.6537 * 10^9

Explanation:

Given that :

Distance (r) = 2.56 × 10^7 m

Using the relation from Kepler's third law of motion :

T2 = [ 4* pi^2/ G (M1 + M2) ]r^3

M1 = mass of earth = 5.97 *10^24

M2 = Mass of satellite = 9.0 × 10^3 kg

G = Gravitational constant = 6.67 *10^-11

T2 = [ (4 x 3.14^2) / 6.67 x 10^-11 ( 9 x 10^3 + 5.97 x 10^24)]/ (2.56 x 10^7)^3

= 1.6537 * 10^9

For every complete revolution the boy makes around the center of the carousel, he travels a distance of 2π (5.0 m) = 10π m, which gives a linear speed of

v = (10π m) / (8.0 s) ≈ 3.927 m/s

Then his centripetal acceleration would be

a = v ² / (5.0 m) ≈ 3.084 m/s²

so that the centripetal force exerted on him has magnitude

F = (45 kg) a ≈ 138.791 N ≈ 140 N

(rounded to 2 significant digits)

Answer: 1 How many grams of KCl will dissolve in 1 liter of H2O at 50 °C? 5. 58.0 g of K2Cr2O7 is added to 100 g H2O at. 0 °C. With constant stirring, to what temp-.                                                                                                                                     2  34 °C? 4. How many grams of KCl will dissolve in 1 liter of H2O at 50 °C? 5. 58.0 g of ... A saturated solution of KClO3 was made with 300 g of H2O at. 34 °C.

Explanation:

Answer:

Explanation:

An object following a circular path can be covering the same distance along the circle's circumference with every passing minute, giving it a constant speed. Since a change in either speed OR direction means a change in velocity, the object's velocity is not constant.

velocity is a vector so therefore direction affects it being constant.

An object's acceleration is the rate its velocity (speed and direction) changes. Therefore, an object can accelerate even if its speed is constant - if its direction changes. If an object's velocity is constant, however, its acceleration will be zero.  

Velocity is a vector so therefore direction affects it being constant.

When an item is moving, its velocity is the rate at which its direction is changing as seen from a certain point of view and as measured by a specific unit of time

An object following a circular path can be covering the same distance along the circle's circumference with every passing minute, giving it a constant speed. Since a change in either speed OR direction means a change in velocity, the object's velocity is not constant. An object's acceleration is the rate its velocity (speed and direction) changes. Therefore, an object can accelerate even if its speed is constant - if its direction changes. If an object's velocity is constant, however, its acceleration will be zero.  

Velocity is a vector so therefore direction affects it being constant.

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Answer:

[tex]\frac{y}{L}[/tex] = 0.66

Hence, the fraction of the length of the rod above water = [tex]\frac{y}{L}[/tex] = 0.66

and fraction of the length of the rod submerged in water = 1 - [tex]\frac{y}{L}[/tex] = 1 - 0.66 = 0.34  

Explanation:

Data given:

Density of the rod = 5/9 of the density of the water.

Let's denote density of Water with w

And density of rod with r

So,

r = 5/9 x w

Required:

Fraction of the length of the rod above water.

Let's denote total length of the rod with L

and length of the rod above with = y

Let's denote the density of rod = r

And density of water = w

So, the required is:

Fraction of the length of the rod above water = y/L

y/L = ?

In order to find this, we first need to find out the all type of forces acting upon the rod.

We know that, a body will come to equilibrium if the net torque acting upon a body is zero.

As, we know

F = ma

Density = m/v

m = Density x volume

Volume = Area x length = X ( L-y)

So, let's say X is the area of the cross section of the rod, so the forces acting upon it are:

F = mg

F = (Density x volume) x g

g = gravitational acceleration

F1 = X(L-y) x w x g (Force on the length of the rod submerged in water)

where,

X (L-y) = volume

w = density of water.

Another force acting upon it is:

F = mg

F2 =  X x L x r x g

Now, the torques acting upon the body:

T1 + T2 = 0

F1 ( y + [tex](\frac{L-y}{2})[/tex] ) g sinФ - F2 x ([tex]\frac{L}{2}[/tex]) x gsinФ = 0

plug in the  equations of F1 and F2 into the above equation and after simplification, we get:

[tex](L^{2} - y^{2} ) . w[/tex] = [tex]L^{2}[/tex] . r

where, w is the density of water and r is the density of rod.

As we know that,

r = 5/9 x w

So,

[tex](L^{2} - y^{2} ) . w[/tex] = [tex]L^{2}[/tex] . 5/9 x w

Hence,

[tex](L^{2} - y^{2} )[/tex] = [tex]\frac{5L^{2} }{9}[/tex]

[tex]\frac{L^{2} - y^{2} }{L^{2} }[/tex] = [tex]\frac{5}{9}[/tex]

Taking [tex]L^{2}[/tex] common and solving for [tex]\frac{y}{L}[/tex], we will get

[tex]\frac{y}{L}[/tex] = 0.66

Hence, the fraction of the length of the rod above water = [tex]\frac{y}{L}[/tex] = 0.66

and fraction of the length of the rod submerged in water = 1 - [tex]\frac{y}{L}[/tex] = 1 - 0.66 = 0.34

Answer: A ,absorption and reflection

Explanation

Absorption and reflection are the two phenomena which describe how the light waves can interact with the wood. Thus, the correct option is A.

Light absorption is a process through which light is absorbed and converted into different form of energy. An example of absorption of light is the process of photosynthesis which takes place in plants. However, light absorption does not occur exclusively in the plants, but in all the creatures and inorganic substances present on this planet.

When a ray of light approaches a smooth polished surface such as a metal surface and the light ray bounces back, it is called as the reflection of light. The incident light ray which lands on the surface is reflected off the surface. The ray that bounces back from the surface is called the reflected ray.

Therefore, the correct option is A.

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Answer:

3.44× 10⁻¹⁹Joules

Explanation:

Energy of the wavelength is expressed using the formula:

E = hc/λ

h is the Planck constant

c is the velocity of light

λ is the wavelength

Given

h = 6.63 × 10^-34 m² kg / s

c = 3×10⁸ m/s

λ = 579nm = 579 × 10⁻⁹m

λ = 5.79× 10⁻⁷m

Substitute the given values into the formula

E = hc/λ

E = (6.63 × 10⁻³⁴× 3×10⁸)/5.79× 10⁻⁷

E = 19.89× 10⁻³⁴⁺⁸/5.79× 10⁻⁷

E = 19.89× 10⁻²⁶/5.79× 10⁻⁷

E = 3.44× 10⁻²⁶⁺⁷

E = 3.44× 10⁻¹⁹Joules

Hence the energy of this wavelength of light is 3.44× 10⁻¹⁹Joules

Answer: d. the low air pressure lowers the boiling point

Explanation:

Note that there cannot be less than 6.1 millibars of liquid water. This fact is important because the Martian surface atmospheric pressure hovers just below that value. Any water that could form from melting water on a warm afternoon will easily vanish into the desiccated Martian atmosphere.

Answer:

3566.26 Watts

Explanation:

From the question given above, the following data were obtained:

Mass (m) of crate = 151 kg

Coefficient of kinetic friction (μ) = 0.399

Velocity (v) = 6.04 m/s

Power (P) =?

Next, we shall determine the normal reaction. This can be obtained as follow:

Mass (m) of crate = 151 kg

Acceleration due to gravity (g) = 9.8 m/s²

Normal reaction (R) = mg

Normal reaction (R) = 151 × 9.8

Normal reaction (R) = 1479.8 N

Next, we shall determine the force applied to move the crate. This can be obtained as follow:

Coefficient of kinetic friction (μ) = 0.399

Normal reaction (R) = 1479.8 N

Force (F) =?

F = μR

F = 0.399 × 1479.8

F = 590.44 N

Finally, we shall determine the power used to move the crate as follow:

Velocity (v) = 6.04 m/s

Force (F) applied = 590.44 N

Power (P) =?

P = F × v

P = 590.44 × 6.04

P = 3566.26 Watts

Therefore, the power used to move the crate is 3566.26 Watts.

Answer:

The answer is temperature lol

Explanation:

:)

Neutrons are required for the stability of nuclei, with the exception of the single-proton hydrogen nucleus. Neutrons are produced copiously in nuclear fission and fusion. They are a primary contributor to the nucleosynthesis of chemical elements within stars through fission, fusion, and neutron capture processes.

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Answer:

9.23m

Explanation:

Max height = u²sin²theta/2g

u is the speed = 34.7m/s

theta is the angle of elevation = 33°

g is the acceleration due to gravity = 9.8m/s²

Substitute into the formula

Max height = 24.7²sin²33/2(9.8)

Max height = 610.09sin²33/2(9.8)

Max height = 610.09(0.29663)/19.6

Max height = 180.97/19.6

Max Height = 9.23m

Hence the max height the football reaches during flight is 9.23m

Answer:

3.6*10¹⁰N/C

Explanation:

The formula for Electric field strength is expressed as:

E = kQ/r²

k is the coulombs constant = 9*10^9Nm²/C²

Q is the charge = 1.00×10°C

r is the distance = 0.50m

Substitute the parameters into the formula as shown:

E = kQ/r²

E =  9*10^9(1)/0.5²

E =  9*10^9/0.25

E = 36*10^9

E = 3.6*10¹⁰N/C

Hence  the electric field strength is 3.6*10¹⁰N/C