At a young age, who has the greatest influence on your choices?
Why do stretching exercises increase flexibility more than cardio exercises?

Answer:

a. by moving the book without acceleration and keeping the height of the book constant

Explanation:

FOR CONSTANT KINETIC ENERGY:

The kinetic energy of a body depends upon its speed according to its formula:

ΔK.E = (1/2)mΔv²

So, for Δv = 0 m/s

ΔK.E = 0 J

So, for keeping kinetic energy constant, the books must be moved at constant speed without acceleration.

FOR CONSTANT POTENTIAL ENERGY:

The potential energy of a body depends upon its height according to its formula:

ΔP.E = mgΔh

So, for Δh = 0 m/s

ΔP.E = 0 J

So, for keeping potential energy constant, the books must be moved at constant height.

So, the correct option is:

a. by moving the book without acceleration and keeping the height of the book constant

Answer:

The cars essentially finish where they started, their displacement is close to zero kilometers. However, the winning vehicles have traveled 500 miles.

The separation between two places of an item in motion is known as displacement. Therefore, it relies on both the starting position and the ending position. Displacement is also the shortest distance between the initial and ultimate places.

The distinction between two locations of an object is known as displacement. Because it has both a direction and magnitude, it qualifies as a vector quantity. The symbol for it is an arrow pointing from the first position to the final position. The cars essentially finish where they started, their displacement is close to zero kilometers. However, the winning vehicles have traveled 500 miles.

Therefore,  their displacement is close to zero kilometers.

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Answer:

Hey

Explanation:

Answer:

one of the graph is postion-time graph while the other one is velocity-time graph

Answer:

Work done, W = 2 J

Explanation:

Given that,

Weight of a book, W = F = 1 N

It is lifted to a height of 2 m

We need to find the work done. It can be calculated using the formula as follows :

W = F d

Put all the values,

W = 1 N × 2 m

W = 2 J

So, 2J of work was done.

Answer:

a. E = 86.36 x 10⁻³ V/m = 86.36 mV/m

b. ρ = 3.6 x 10⁻⁷ Ωm

Explanation:

a.

The electric field in terms of the voltage is given by the following formula:

E = V/d

where,

E = Electric Field in the Wire = ?

V = Potential Difference = 3.8 V

d = distance between the points = 44 m

Therefore,

E = 3.8 V/44 m

E = 86.36 x 10⁻³ V/m = 86.36 mV/m

b.

Now, from Ohm's Law:

V = IR

R = V/I

where,

R = Resistance of wire = ?

I = Current = 3 A

Therefore,

R = 3.8 V/3 A

R = 1.27 Ω

Now, the resistance of a wire can be given as:

R = ρL/A

where,

ρ = resistivity of material = ?

L = Length = 44 m

A = Cross-sectional area = πr² = π(0.002 m)² =  1.25 x 10⁻⁵ m²

Therefore,

1.27 Ω = ρ*44 m/1.25 x 10⁻⁵ m²

(1.27 Ω)(1.25 x 10⁻⁵ m²)/44 m = ρ

ρ = 3.6 x 10⁻⁷ Ωm

Answer:

However, those astronauts would experience a second spectacle: A solar eclipse caused by the Earth – the Sun disappearing behind the dark disc of the Earth. When Earth inhabitants witness a lunar eclipse, Moon inhabitants would, simultaneously be witnessing a solar eclipse.

Answer:

-63.6m/s

Explanation:

Given parameters:

Initial velocity  = 5m/s

Time of flight  = 7s

Unknown:

Velocity of the eraser after 7s = ?

Solution:

To solve this problem, we have to use the right motion equation which is given below;

          v  = u - gt

v is the final velocity

u is the initial velocity

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

t is the time taken;

  Now insert the parameters and solve for v;

     v  = 5  - (9.8 x 7)  

    v   = -63.6m/s

Answer:

O.75KΩ

Explanation:

We measure the time constant τ, using the formula τ = L/R,

t is in seconds, then we have R to be the value of the resistor which is measured in ohms and also L is the value of the inductor which is measured in Henries.

Since t = L/R

We make R subject of the formula

R = L/τ

= 3/4x10-3

= 0.00075

= 0.75 KΩ

So we have it that the first Option (A) is the correct answer to the question

The resistance to be added is required.

The resistance added should be A. [tex]0.75\ \text{k}\Omega[/tex]

L = Inductance = 3 H

[tex]\tau[/tex] = Time constant = 4 ms

R = Resistance

Time constant is given by

[tex]\tau=\dfrac{L}{R}\\\Rightarrow R=\dfrac{L}{\tau}\\\Rightarrow R=\dfrac{3}{4\times 10^{-3}}=750\ \Omega=0.75\ \text{k}\Omega[/tex]

The resistance added should be [tex]0.75\ \text{k}\Omega[/tex]

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Answer:

The pH scale measures of how acidic or basic water is.

The pH scale also measures whether there is more hydronium or hydroxide in a solution.

Explanation:

The range goes from 0-14, with 7 being neutral. Less than 7 indicates acidity and more than seven indicates the substance is a base.

Answer:

29223.6J

Explanation:

Given parameters:

Mass of Piano = 852kg

Height of lifting  = 3.5m

Unknown:

Gravitational potential energy  = ?

Solution:

The gravitational potential energy of a body can be expressed as the energy due to the position of a body;

  G.P.E  = mgh

m is the mass

g is the acceleration due to gravity

h is the height

 Now insert the given parameters and solve;

   G.P.E  = 852 x 9.8 x 3.5 = 29223.6J

Answer:

V₀ₓ = 9.2 m/s

Nearest answer:

D) 8.9 m/s

Explanation:

First we find the time taken by the pumpkin to hit the car. For that purpose we apply 2nd equation of motion to the pumpkin:

h = V₀y t + (1/2)gt²

where,

h = height of building = 10.4 m

V₀y = vertical component of initial speed = 0 m/s

t = time = ?

g = 9.8 m/s²

Therefore,

10.4 m = (0 m/s)(t) + (1/2)(9.8 m/s²)t²

t² = (10.4 m)(2)/(9.8 m/s²)

t = √[2.122 s²]

t = 1.45 s

Now, we analyze horizontal motion for horizontal component of initial velocity. We assume air friction to be zero so that the horizontal motion is uniform. Therefore,

s = V₀ₓ t

where,

s = horizontal distance between building and car = 13.4 m

V₀ₓ = Horizontal Component of Initial Velocity = ?

Therefore,

13.4 m = V₀ₓ(1.45 s)

V₀ₓ = 13.4 m/1.45 s

V₀ₓ = 9.2 m/s

Answer:

A: Soil

Explanation:

Protists need a moist environment to survive, and shallow ponds, oceans, and blood is all moist. So, the answer would be the soil, because that is the least moist environment out of these options.

Answer:

1.45

Explanation:

Refractive index of the liquid is given as;

Refractive index = [tex]\frac{speed of light in vacuum}{speed of light in liquid}[/tex]

But,

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

Since a certain light of specific wavelength was used during the same time, let the time be represented by t.

So that;

speed of light in vacuum = [tex]\frac{3500}{t}[/tex]

speed of light in the liquid = [tex]\frac{2350}{t}[/tex]

Refractive index = [tex]\frac{3500}{t}[/tex] ÷ [tex]\frac{2350}{t}[/tex]

                            = [tex]\frac{3500}{t}[/tex] x [tex]\frac{t}{2350}[/tex]

Refractive index = [tex]\frac{3500}{2350}[/tex]

                          = 1.4536

                          = 1.45

The refractive index of the liquid is 1.45.

Answer:

Explanation:

cross sectional area = .4 x .2 = .08 m²

Let n be the number of blocks required to make pressure = 2 atm

169 x n / .08 = 2 x 10⁵ N / m²

169 x n = .16 x 10⁵

n = 94.67

or 95 blocks .

Answer:

The stress is  [tex]\sigma = 1.218*10^{6} \ N/m^2[/tex]

Explanation:

From the question we are told that

   The diameter of the post is  [tex]d = 29 \ cm = 0.29 \ m[/tex]

   The length is [tex]L = 2.0 \ m[/tex]

    The weight of the loading mass

Generally  the  radius of the post is mathematically represented as

     [tex]r = \frac{0.29}{2}[/tex]

=>   [tex]r = 0.145 \ m[/tex]

Generally the area of the post is  

       [tex]A = \pi r^2[/tex]

=>     [tex]A = 3.14 * 0.145 ^2[/tex]

=>     [tex]A = 0.066 \ m^2[/tex]

Generally the weight exerted by the load is mathematically represented as

        [tex]F = m * g[/tex]

=>      [tex]F = 8200 * 9.8[/tex]

=>      [tex]F = 80360 \ N[/tex]

Generally the stress is mathematically represented as

         [tex]\sigma = \frac{F}{A}[/tex]

=>      [tex]\sigma = \frac{80360 }{0.066}[/tex]

=>      [tex]\sigma = 1.218*10^{6} \ N/m^2[/tex]

Explanation:

U = 40m/s

V = 30m/s

T = 5 sec

A = ?

[tex]a = \frac{u - v}{t}[/tex]

[tex]a = \frac{40 - 30}{5}[/tex]

[tex]a = \frac{10}{5}[/tex]

[tex]a = 2[/tex]

since it's decreasing in speed, The acceleration will be " - 2.0ms^-2 " or " - 2.0m/s^2 "

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The iron has, because it's displacing more water than the wood is.

Answer:

Explanation:

pV = nrT

n = PV/RT

n = (100*10^3)(.01)/(300*0.082057)

n = 40.62 moles

Answer:

14.2

Explanation:

find horizontal force of the weight = 2.5kg x 9.8 Sin30 = 12.3 N

to prevent the sliding she needs to pull horizontally

Fh = 12.3 /Cos 30 =14.2N

Answer:

a) The potential energy of the system is 1/9 of the total mechanical energy, when [tex]x= \frac{1}{3}\cdot A[/tex].

b) The fraction of the total mechanical energy that is kinetic if the displacement is 1/2 the amplitude is 1/2.

c) The maximum kinetic energy is increased by a factor of 9.

Explanation:

a) From Mechanical Physics, we remember that the mechanical energy of mass-spring system ([tex]E[/tex]), measured in joules, is the sum of the translational kinetic energy ([tex]K[/tex]), measured in joules, and elastic potential energy ([tex]U[/tex]), measured in joules. That is:

[tex]E = K + U[/tex] (1)

By definitions of translational kinetic energy and elastic potential energy, we have the following expressions:

[tex]K = \frac{1}{2}\cdot m \cdot v^{2}[/tex] (2)

[tex]U = \frac{1}{2}\cdot k\cdot x^{2}[/tex] (3)

Where:

[tex]m[/tex] - Mass, measured in kilograms.

[tex]v[/tex] - Velocity of the mass, measured in meters per second.

[tex]k[/tex] - Spring constant, measured in newtons per meter.

[tex]x[/tex] - Elongation of the spring, measured in meters.

If we know that [tex]U = \frac{1}{9}\cdot E[/tex], [tex]k = k[/tex] and [tex]E = \frac{1}{2}\cdot k \cdot A^{2}[/tex], then:

[tex]\frac{1}{18}\cdot k\cdot A^{2} = \frac{1}{2}\cdot k\cdot x^{2}[/tex]

[tex]\frac{1}{9}\cdot A^{2} = x^{2}[/tex]

[tex]x= \frac{1}{3}\cdot A[/tex]

The potential energy of the system is 1/9 of the total mechanical energy, when [tex]x= \frac{1}{3}\cdot A[/tex].

b) If we know that [tex]k = k[/tex], [tex]x = \frac{1}{2}\cdot A[/tex] and [tex]E = \frac{1}{2}\cdot k \cdot A^{2}[/tex], then the equation of energy conservation associated with the system is:

[tex]\frac{1}{2}\cdot k\cdot A^{2} = \frac{1}{4}\cdot k\cdot A^{2}+K[/tex]

[tex]K = \frac{1}{4}\cdot k\cdot A^{2}[/tex]

The fraction of the total mechanical energy that is kinetic if the displacement is 1/2 the amplitude is 1/2.

c) From the Energy Conservation equation associated with the system, we know that increasing the amplitude by a factor of 3 represents an increase in the elastic potential energy by a factor of 9. Then, the maximum kinetic energy is increased by a factor of 9.

Answer:

B.

Explanation:

Answer:

h = 51.75 m

nearest answer is:

53.4 m

Explanation:

First we analyze the horizontal motion. Since, the air friction is assumed to be negligible. Hence, the horizontal motion shall be uniform. Therefore,

s = V₀ₓ t

where,

s = horizontal distance = 39 m

V₀ₓ = Horizontal Initial Velocity = 12 m/s

t = time = ?

Therefore,

39 m = (12 m/s)t

t = 39 m/12 m/s

t = 3.25 s

Now, we analyze the vertical motion. Applying newton's second equation of motion to vertical motion:

h = V₀y t + (1/2)gt²

where,

h = height of cannon = ?

V₀y = initial vertical velocity = 0 m/s

g = 9.8 m/s²

Therefore,

h = (0 m/s)(3.25 s) + (1/2)(9.8 m/s²)(3.25 s)²

h = 51.75 m

Answer:

Delivery truck

Explanation:

Answer:

Consider an n-type silicon semiconductor at T = 300°K in which Nd = 1016 cm-3 and Na = 0. The intrinsic carrier concentration is assumed to be ni = 1.5 x 1010 cm-3. - Comment Nd >> ni, so that the thermal-equilibrium majority carrier electron concentration is essentially equal to the donor impurity concentration.

Explanation:

Answer:

[tex]14400\ \text{N}[/tex], Attractive

[tex]3240\ \text{N}[/tex], Repulsive

Explanation:

[tex]q_1[/tex] = -20 μC

[tex]q_2[/tex] = 50 μC

r = Distance between the charges = 2.5 cm

k = Coulomb constant = [tex]9\times 10^9\ \text{Nm}^2/\text{C}^2[/tex]

Electrical force is given by

[tex]F=\dfrac{kq_1q_2}{r^2}\\\Rightarrow F=\dfrac{9\times 10^9\times (-20\times 10^{-6})\times (50\times 10^{-6})}{(2.5\times10^{-2})^2}\\\Rightarrow F=-14400\ \text{N}[/tex]

The magnitude of force each sphere will experience is [tex]14400\ \text{N}[/tex]

Since the charges have opposite charges they will attract each other.

Now the charges are brought into contact with each other so the resultant charge will be

[tex]q=\dfrac{q_1+q_2}{2}\\\Rightarrow q=\dfrac{-20+50}{2}\\\Rightarrow q=15\ \mu\text{C}[/tex]

[tex]F=\dfrac{kq^2}{r^2}\\\Rightarrow F=\dfrac{9\times 10^9\times (15\times 10^{-6})^2}{(2.5\times 10^{-2})^2}\\\Rightarrow F=3240\ \text{N}[/tex]

The magntude of the force the spheres experience will be [tex]3240\ \text{N}[/tex]

The spheres have the same charge now so they will repel each other.

Answer:

Explanation:

Velocity of train 130 km /hr

distance of crossing s = 500 m = .5 km

Time taken by train to reach crossing = .5 / 130 = .003846 hr = 13.85 s

Time taken by gangster to reach the crossing = t

initial velocity u = 100km/h = 27.77 m /s

distance of crossing s = 750 m

acceleration a = 4 m /s

s = ut + .5 a t²

750 = 27.77 t + .5 x 4 x t²

2 t² + 27.77 t - 750 = 0

t = - 27.77 ± √(27.77² + 4 x 2 x 750) / 2 x 2

= - 27.77 ±√ ( 771.17 + 6000) / 4

= - 27.77 ±82.28 / 4

= 13.62 s

So this time is less than time taken by train so it will be able to cross the crossing before train arrives .

Answer:

The minimum inductance needed is 2.78 H

Explanation:

Given;

frequency of the AC, f = 26.5 Hz

the root mean square voltage in the circuit, [tex]V_{rms}[/tex] = 41.2 V

the maximum current in the circuit, I₀ = 126 mA

The root mean square current is given by;

[tex]I_{rms} = \frac{I_o}{\sqrt{2} } \\\\I_{rms} = \frac{126*10^{-3}}{\sqrt{2} }\\\\I_{rms} =0.0891 \ A[/tex]

The inductive reactance is given by;

[tex]X_l = \frac{V_{rms}}{I_{rms}} \\\\X_l= \frac{41.2}{0.0891}\\\\X_l = 462.4 \ ohms[/tex]

The minimum inductance needed is given by;

[tex]X_l = \omega L\\\\X_l = 2\pi fL\\\\L = \frac{X_l}{2\pi f}\\\\L = \frac{462.4}{2\pi *26.5}\\\\L = 2.78 \ H[/tex]

Therefore, the minimum inductance needed is 2.78 H