A wooden block meauring 40cm x 10cm x 5cm has a mass 850gm . find the density of wood?
please answer me.​

Answer:

f = 4.67 cm

Explanation:

Here, we can use the thin lens formula, as follows:

[tex]\frac{1}{f}= \frac{1}{p}+ \frac{1}{q}\\\\[/tex]

where,

f = focal length of lens = ?

p = distance of object from lens = 12.4 cm

q = distance of image from lens = 7.5 cm

Therefore,

[tex]\frac{1}{f} =\frac{1}{12.4\ cm} +\frac{1}{7.5\ cm}\\\\\frac{1}{f} = \frac{1}{4.67\ cm}[/tex]

f = 4.67 cm

Answer:

C

Explanation:

edge 2020... Using elimination it's the only one that makes sense.

The statement third "an increase in the distance between the objects causes a greater change in the gravitational force than the same increase in mass" is correct.

The gravitational force is a force that attracts all mass-bearing objects. The gravitational force is referred to as attractive because it always strives to pull masses together rather than pushing them apart.

As we know, the gravitational force is given by:

[tex]\rm F = \dfrac{Gm_1m_2}{r^2}[/tex]

Where, G is the gravitational constant.

m1 and m2 are masses.

r is the distance between the masses.

From the data given in the table, shows that:

The gravitational force is indirectly proportional to the square of the distance.

Thus, the statement third "an increase in the distance between the objects causes a greater change in the gravitational force than the same increase in mass" is correct.

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Answer:

D

Explanation:

D ok ok ok ok bye

The correct statement is that the alcohol has lower boiling point than water. The correct option is B.

At the boiling point, the pressure exerted by the surroundings on a liquid equals the pressure exerted by the liquid's vapor, under this condition, adding heat outcomes in the transformation of the liquid into its vapor without raising the temperature.

The boiling point of alcohol is low. Because there is less hydrogen bonding between ethanol molecules than between water molecules.

The ethanol requires less energy to vaporize than water, and water has a higher boiling point than ethanol.

The boiling point of a liquid can be known by utilizing the capillary method, that encompasses placing an inverted capillary in the liquid of interest as well as heating it.

Thus, the correct option is B.

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Answer: A. Ar

Explanation: not anything else besides Ar

Answer:

i have no idea i came here to find out too :(

Explanation:

B. The energy transformation that is correct is From C to D, kinetic energy is transformed into gravitational potential energy.

The law of conservation of energy states that energy can neither be created nor destroyed but can be transformed from one form to another.

Energy transformation in the pendulum;

Thus, the energy transformation that is correct is From C to D, kinetic energy is transformed into gravitational potential energy.

option B is the correct answer.

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Answer:

B is Correct

Explanation:

From C to D, kinetic energy is transformed into gravitational potential energy.

Answer:

D

Explanation:

Answer:

Option A

Explanation:

The graph for this problem must depict the following ""Increased allocation of resources to reproduction relative to growth diminished future fecundity."

Hence, the survivor ship must be on the Y axis and the resources on the X axis.

Here the resources include the number of seeds produced.

hence, the higher is the number of seeds (resource), the lower is the survivorship (future fecundity)

Hence, option A is correct

Answer: 3.13 m

Explanation:

Given

mas of the ball is m=10 kg

The ball rolls down a vertical distance of 5 m

Spring constant of spring is [tex]k=100\ N/m[/tex]

Here, the potential energy of the ball converted into kinetic energy which in turn converts into elastic potential energy

[tex]\Rightarrow mgh=\frac{1}{2}kx^2\quad [\text{x=compression in the spring}]\\\\\Rightarrow 10\times 9.8\times 5=\frac{1}{2}\cdot 100\cdot x^2\\\Rightarrow x=\sqrt{9.8}\\\Rightarrow x=3.13\ m[/tex]

Thus, the spring compresses by 3.13 m.

Answer:

In fission, energy is gained by splitting apart heavy atoms, for example uranium, into smaller atoms such as iodine, caesium, strontium, xenon and barium, to name just a few. However, fusion is combining light atoms, for example two hydrogen isotopes, deuterium and tritium, to form the heavier helium.

Explanation:

I hope this helped you

(Sorry If it didn't)

Answer:

E = 1.711 MeV

Explanation:

From the law of the conservation of energy:

[tex]K.E_{e}+K.E_p + E_{e}+E_{p} = 2 E[/tex]

where,

[tex]K.E_e=K.Ep=[/tex] the kinetic energy of positron and electron = 1.2 MeV

[tex]E_e=E_p =[/tex] Rest energy of the electron and the positron = 0.511 MeV

E = Energy of Photon = ?

Therefore,

[tex]1.2\ MeV + 1.2\ MeV + 0.511\ MeV + 0.511\ MeV = 2E\\\\E = \frac{3.422\ MeV}{2}\\\\[/tex]

E = 1.711 MeV

Answer:

upward

Explanation:

In the electromagnetic system of force if the direction of motion of proton does not changes it means that the electric and magnetic forces are such a ways that they are cancelling each other's effect.

Since, electric field lines will exert a force on the proton to the west, hence, the magnetic force must force it to the east. It is well known that magnetic force acts perpendicular to the direction of magnetic field.  magnetic field should point upward direction.

Answer:

False.

Explanation:

The voltage of a disconnected charged capacitor decreases when the plates are brought closer together because the capacitance is inversely proportional to the area. If the area between plates decreases, its capacitance increases and vice versa. There is direct relationship between voltage of a disconnected charged capacitor and plates. If the distance between plates decreases, the voltage of a disconnected charged capacitor is also decreases while on the other hand, if the distance between plates increases, the voltage of a disconnected charged capacitor is also increases.

Answer:

ω = 0.05 rad/s

Explanation:

In order to produce the acceleration equal to the acceleration due to gravity at the surface of Earth, the centripetal acceleration must be equal to the value  of g:

[tex]a_c = g\\g = \frac{v^2}{r}\\\\but,\ v=r\omega\\therefore,\\\\g = \omega^2r\\\\\omega = \sqrt{\frac{g}{r}}[/tex]

where,

ω = angular speed = ?

g = acceleration due to gravity on the surface of the Earth = 9.81 m/s²

r = radius of cylinder = 8 km/2 = 4 km = 4000 m

Therefore,

[tex]\omega = \sqrt{\frac{9.81\ m/s^2}{4000\ m}}[/tex]

ω = 0.05 rad/s

Answer:

5.0-5.5 is the answer to your question

Answer:

M = 1.90 Kg

Explanation:

Given data: mass = 2.5 Kg

radius R = 0.8 m

angular velocity ω = 1.5 rad/s

Angular momentum L =0.5×Iω^2

Where, I  is the moment of inertia of the spinning disc.

I = 0.5MR^2

I = 0.5×2.5×0.8^2

I = 0.8 Kg/m^2

Then L = 0.5×0.8×1.5^2 = 0.8×2.25 = 0.9 Kg-m^2/sec

Let unknown mass be M

New mass of disc = (2.5+M) Kg, R = 0.8 m

New I = 0.5(2.5+M)(0.8)^2

Since, angular momentum is conserved

Angular momentum before = angular momentum after

0.5×0.5(2.5+M)(0.8)^2×(1.13)^2 = 0.9

Solving for M we get

0.204304(2.5+M)=0.9

M = 1.90 Kg

Answer:

 y_lower = 0.915 m,   y_superior = 1,905 m

Explanation:

In this exercise we use the law of reflection for a flat mirror.

         θ’= θ

To see the feet of the person a ray of light that part of them must reach the bottom of the mirror and its reflection has to reach the eyes.

As the law of reflection the incident and reflected angles are equal, the distance from the floor to the point where the two rays (incident and reflected) touch the mirror must be symmetrical, oses from the floor

           y = 1.83 / 2

           y = 0.915 m

To see the head, a ray of light that comes from the tip of the head and is reflected in the mirror must reach the eyes. As the head is 0.15 m above the eyes and the incident and reflected rays have the same angle, the mirror must be at half the height, that is, the mirror is 0.075 m below the tip of the head.

In summary

* the bottom of the mirror is 0.915 m from the ground

* the top of the mirror is at 1.83 + 0.075

                 y_superior = 1,905 m

ground

Answer:

Explanation:

The law is about how object will be deformed when certain amount force is  applied. Elastic limit is a point where object will not return its previous shape after being deformed

Answer:

The correct answer is -

B. The velocity would double (v = 2v).

C. The wavelength would be half (λ = λ/2).

Explanation:

A wave has a speed or velocity that is related to the wavelength of the wave and the frequency of the wave and this relationship can be represented by the following equation-

Wave velocity V = Wavelength (λ) * Frequency (f)

Frequency (f) = Velocity (V) / Wavelength(λ).

The frequency and wavelength are inversely proportional and frequency and velocity are directly proportional to each other.

So, if f = 2f then,

putting value in the formula,

2f = 2v/λ, which means, f = 2v and f = λ/2

when the frequency is doubled, the wavelength will be halved and velocity will be doubled.

Answer:

a. ε = 21,014sin(120πt) V

b. 0.476cosec(120πt)  

Explanation:

a. Induced emf

We know the induced emf, ε = -dΦ/dt where Φ = magnetic flux through coil = NABcosθ where N = number of turns of coil =, 100, A = area of coil = 10 ft × 6 ft = 60 ft² = 60 × 1 ft² = 60 × (0.3048)² m² = 5.574 m², B = magnetic field strength = 0.1 T and θ = angle between B and normal to A = ωt.

So, Φ = NABcosθ = 100 × 5.574 m² × 0.1 T cosθ  = 55.74cosθ Tm²

So, ε = -dΦ/dt = ε = -d(55.74cosθ Tm²)/dt = -d(55.74cosθ Tm²)/dθ × dθ/dt = -55.74 ×(-sinθ) Tm²)/dθ × ω (ω = dθ/dt = angular frequency of shaft = 2πf where f = frequency of rotor = 60 Hz )

ε = 55.74sinθ Tm²) × 2πf

ε = 55.74sinθ Tm²) × 2π(60 Hz)

ε = 6689πsinθ V

ε = 21,014sinθ V

ε = 21,014sinωt V

ε = 21,014sin(2πft) V

ε = 21,014sin(2π(60 Hz)t) V

ε = 21,014sin(120πt) V

b. Current in coil

Since power P = Iε where I = current and ε = induced emf = 21,014sinθ V.

Since power, P = 10 kW = 10000 W

I = P/ε

= 10000 W/21,014sinθ V

= 0.476/sinθ

= 0.476cosecθ

= 0.476cosecωt

= 0.476cosec(120πt)  

The maximum current is obtained when θ = 90°

I =  10000 W/21,014sin90 V

I = 10000 W/21,014 V

I = 0.476 A

I = 476 mA