C.
A palm fruit dropped to the ground from the top of
a tree 45m tall. How long does it take to reach the
ground? A. 9s B. 4.5s C. 6 D. 7.5s E. 35
(g = 10ms2).​

Answer:

Second, fundamental unit of time, now defined in terms of the radiation frequency at which atoms of the element cesium change from one state to another. The second was formerly defined as 1/86,400 of the mean solar day—i.e., the average period of rotation of the Earth on its axis relative to the Sun.

source britannica

Explanation:

Answer:

Explanation:

We need the power equation here:

P = W/t where W is work and is defined as

W = F*displacement.

Force is a measure in Newtons, which is also weight. We have the mass of the piano, but we need to find the weight:

w = mg so

w = 166(9.8) so

w = 1600N, rounded to the correct number of sig dig. We use that now in the power equation:

[tex]4560=\frac{(1600)(15)}{t}[/tex] and isolating the unknown:

[tex]t=\frac{(1600)(15)}{4560}[/tex] so

t = 5.3 seconds

Answer:

B. its consist of waves of varying lengtu

Answer:

B. After a photon of light is absorbed by certain metals, electrons are found to be ejected from the metals. This is because the energy contained in the massless photon is used to eject an electron with mass out of the metal.

Explanation:

Before, in the early days, it was proposed to form a combined theory by joining the theory of conservation of mass and the theory of conservation of energy and form a combined theory of conservation of mass-energy. It was done to explain a particular theory of [tex]$\text{photoelectric effect}$[/tex].

The [tex]$\text{photoelectric effect}$[/tex] is the emission of the electrons form the surface of a metal when light energy strikes on it. Here, in this phenomenon, both mass and energy is conserved.

When the light strikes a metal surface, electrons gets ejected from the surface. The energy of the photon is used to eject the electron form the metal surface.

Answer:

lhchccyohchocohchocoyxtidts8ts58d85dtitxicyi

Answer:hot air

Explanation:Hot air goes up, so when you put it in a hot air balloon fire is placed at the oppening to creat hot air and lift the balloon! :)

Answer: [tex]14.64\ N[/tex]

Explanation:

Given

Inclination of ramp is [tex]\theta=15^{\circ}[/tex]

Rope is inclined [tex]\phi=60^{\circ}[/tex] to the horizontal

Weight of cart [tex]W=40\ lb[/tex]

from the diagram, rope is at angle of [tex]45^{\circ}[/tex] w.r.t ramp

Sine component of weight pulls down the cart Cosine component of force applied through rope held it at the position

[tex]\Rightarrow 40\sin 15^{\circ}=F\cos 45^{\circ}\\\\\Rightarrow F=40\cdot \dfrac{\sin 15^{\circ}}{\cos 45^{\circ}}\\\\\Rightarrow F=40\times 0.366\\\Rightarrow F=14.64\ N[/tex]

c. a natural process

It is a natural process

Answer: [tex]-4.3\ J,\ 9\ J[/tex]

Explanation:

Given

(a)

Heat transfer [tex]Q=-7.9\ J\quad \text{taken}[/tex]

Work done [tex]W=-3.6\ J\quad \text{on the system}[/tex]

Change in the internal kinetic energy is

[tex]\Delta U=Q-W\\\Rightarrow \Delta U=-7.9-(-3.6)\\\Rightarrow \Delta U=-4.3\ J[/tex]

(b)

Heat transfer [tex]Q=1.5\ J\quad \text{given}[/tex]

Work done [tex]W=-7.5\ J\quad \text{on the system}[/tex]

Change in the internal kinetic energy is

[tex]\Delta U=Q-W\\\Rightarrow \Delta U=1.5-(-7.5)\\\Rightarrow \Delta U=9\ J[/tex]

Answer:

Hello There!!

Explanation:

They are produced by the photodissociation of negatively charged hydrogen ions (H−).

hope this helps,have a great day!!

~Pinky~

SOLVED DOWN BELOW

Explanation:

In series the same current goes thru both resistors, equiv resistance is 200 ohms, then using ohms law

I = 25/200

I= .125 amps or 125 ma

__________

R= r1 * r2 / r1 +r2

R= 100 * 100 / 100 + 100

R= 10000 / 200

R= 50 ohms

Answer:

The speed of the vehicle is 156 miles per hour.

Explanation:

Let suppose that the Maglev, that is, a vehicle who works on the principle of superconductive magnetic levitation, moves at constant speed. Hence, the speed of the vehicle ([tex]v[/tex]), in miles per hour, is defined by this kinematic model:

[tex]v = \frac{s}{t}[/tex] (1)

Where:

[tex]s[/tex] - Travelled distance, in miles.

[tex]t[/tex] - Time, in hours.

If we know that [tex]s = 624\,mi[/tex] and [tex]t = 4\,h[/tex], then the speed of the vehicle is:

[tex]v = \frac{624\,mi}{4\,h}[/tex]

[tex]v = 156\,\frac{mi}{h}[/tex]

The speed of the vehicle is 156 miles per hour.

Answer:

Explanation:

Answer:

m of solid = 600g = 0.6kg

T=40°C

It was placed in a calorimeter that contains 25g(0.025kg) of water at 10°C

Now. We would have considered the calorimeter in this solving because it will be at the same temp as the water which it is holding. Example... If you put a hot water inside a Cup... The cup itself will become hot and have the same temp as the water you put in it ...

But in this question... We'll Ignore the Calorimeter and the heat gained by it since no parameter was given for it and also We don't know the material which the calorimeter is made of.

So

Since the Solid is at a higher temp(40°)... It will lose heat to water; which is at a lower temp.

From the question... THE EQUILIBRIUM TEMPERATURE REACHED IS 25°C

Then

Temp Change for solid(heat loss) = 40-25=15°C

Temp Change for water(heat gain)= 25-10 =15°C

Heat lost by solid = Heat gained by water

MC∆T = MC∆T

0.6 x C x 15 = 0.025 x 4180 x 15

C= 0.025x4180x15÷(0.6x15)

C= 174.16 ~ 174J/Kg.K.

OPTION C IS LEGIT

Answer:

The height of building should be 98.13 m plus the height of Daniel. Since the 63° was measured from his eye level.

Explanation:

The answer for this question is D

Answer:

Explanation:

Use the one-dimensional equation:

[tex]v_f=v_0+at[/tex] which says that the final velocity of a falling object is equal to its initial velocity times the acceleration of gravity times the time it takes to fall. We have the final velocity, -14.5 (negative because its direction is down and down is negative), initial velocity is 0 (because it was held still by someone before it was dropped), and acceleration is -9.8 (negative again, because direction is down while acceleration increases). Filling in:

-14.5 = 0 - 9.8t and

-14.5 = -9.8t so

t = 1.5 seconds

This question is incomplete, the complete question is;

People who do very detailed work close up, such as jewelers, often can see objects clearly at much closer distance than the normal 25 cm.

a) What is the power in D of the eyes of a woman who can see an object clearly at a distance of only 8.50 cm? (Assume the lens-to-retina distance is 2.00 cm.)

b) What is the size in mm of an image of a 8.00 mm object, such as lettering inside a ring, held at this distance? (Include the sign of the value in your answer.)  __ mm

Answer:

1) the power in D of the eyes of a woman is 61.7647 D

2) the size in mm of an image of a 8.00 mm object is -1.882 mm

Explanation:

Given the data in the question;

a) power in D of the eyes of woman who can see an object clearly at a distance of only 8.5 cm and the lens-to-retina distance is 2.00 cm,

so

u = 8.5 cm = ( 8.5 / 100 )m = 0.085 m

v = 2.00 cm = ( 2 / 100 )m =  0.02 m

Now, we know that power of lens p = 1 / u + 1 / v

so we substitute

p = ( 1 / 0.085 ) + ( 1 / 0.02 )

p = 11.7647 + 50

p = 61.7647 D

Therefore,  the power in D of the eyes of a woman is 61.7647 D

b) What is the size in mm of an image of a 8.00 mm object, such as lettering inside a ring, held at this distance? (Include the sign of the value in your answer.)

we know that;

m = -v / u

we substitute

m = -0.02 / 0.085

m = -0.2353

since H₀ = 8.0 mm

H[tex]_i[/tex] = m × H₀

H[tex]_i[/tex] = -0.2353 × 8.0

H[tex]_i[/tex] = -1.882 mm

the size in mm of an image of a 8.00 mm object is -1.882 mm

Answer:

The sensitivity of the device = 1.234 Hz per km

Explanation:

Given  

Frequency (f) = 10 gHz

Speed of the car = 120 Km/h

As per the doppler’s effect

V = (change in frequency /frequency) *(c/2)

Substituting the given values, we get –  

Change in frequency = {(2*10^9*120)/(3*10^8)} * (1000/3600)

Change in frequency =  37.03 Hz

b) speed of light = wavelength * frequency

3*10^8 = wavelength * 10*10^9

Wavelength = 0.03 m

Sensitivity = change in frequency /wavelength = 37.03/0.03 = 1234 Hz/m

1.234 Hz per km

Answer:

Resistance is as large as 2.8 ohm

Explanation:

Complete question

A 3.0 A current is maintained in a simple circuit that consists of a resistor between the terminals of an ideal battery. If the battery supplies energy at a rate of 25 W, how large is the resistance?

Solution -

The relation between Power and current is as follows  

P = I^2*R

R = P/I^2

Were P = Power

R = resistance and

I = current

Given-  

P = 25 W  

I = 3.0 A

Substituting the given values, in above equation, we get -  

R = 25/3.0^2

R = 2.8 ohm

Answer:

doubled

Explanation:

When thrust is double so will the pressure I hope this helps

enjoy

Answer:

 K = 7.56 10⁻⁴ J

Explanation:

The rotational kinetic energy is

        K = ½ I w²

They ask us for the kinetic energy of the wheel, which can be approximated as a thin ring, its moment of inertia is

         I = M r²

the linear speed of the gerbils is equal to the linear speed of the wheel. The linear and rotational variables are related

          v = w r

          w = v / r

   we substitute

         K = ½ (M r²) v² / r²

         K = ½ M v²

let's calculate

         K = ½ 5 10⁻³ 0.55²

         K = 7.56 10⁻⁴ J

Answer:

-10miles/hr²

Explanation:

a = ∆v/∆t

Where:

a = acceleration (miles/hr²)

∆V = change in velocity (miles/hr)

t = time (hour)

The change in time is from 2:00 - 4:00 ∆t = 2 hours.

The distance covered is as follows: 20miles/hour - 40 miles/hr

∆v = -20miles/hr

Using a = ∆v/∆t

a = -20/2

a = -10miles/hr²

Answer:

a PNP transistor used as an amplifier

Explanation:

The diagram show a PNP transistor used as an amplifier.PNP transisitor having one 2 P type and the 1 N type of semiconductor.

This bipolar PNP junction transistor is made up of three layers of semiconductor material, two of which are P-type & one of which is N-type. It consists of three terminals.

The transistor's emitter allows it to supply the majority of charge carriers. In relation to the ground, the emitter always is forward biased.

As a result, the base receives the vast majority of charge carriers. A transistor's emitter is strong and of modest size.

The collector collects the vast majority of the charge carrier delivered by the emitter. Reverse bias is always present at the collector-base junction.

The charge collector region is moderately mixed and capable of collecting the charge.

The diagram shows a transistor used in a circuit.

A signal with a small change in voltage is input into a circuit that includes a transistor connected to 4 resistors and 2 capacitors. The signal output from the transistor has a much larger change in voltage than the input.

The diagram show a PNP transistor used as an amplifier.

Hence option C is correct.

To learn more about the PNP transistors refer to the link;

https://brainly.com/question/1492057

Answer:

a)  [tex]v=181.497m/s[/tex]

b)  [tex]\lambda=1.2[/tex]

c)  [tex]F=151.248hz[/tex]

Explanation:

From the question we are told that:

Linear density [tex]\rho=8.5 x 10-3 kg/m[/tex]

Tension [tex]T= 280 N[/tex]

Length of string [tex]l= 1.8 m[/tex]

a)

Generally the equation for Speed of travelling wave is mathematically given by

 [tex]v=\sqrt{\frac{T}{\rho}}[/tex]

 [tex]v=\sqrt{\frac{280}{8.5*10^{-3}}[/tex]

 [tex]v=181.497m/s[/tex]

b)

From the Drawing

Wavelength is given as

 [tex]\lambda=\frac{2L}{3}[/tex]

 [tex]\lambda=\frac{2*1.8}{3}[/tex]

 [tex]\lambda=1.2[/tex]

c)

Generally the equation for Frequency of travelling wave is mathematically given by

 [tex]F=\frac[v}{\lambda}[/tex]

 [tex]F=\frac[181.497}{1.2}[/tex]

 [tex]F=151.248hz[/tex]

Answer:

Resultant displacement = 1222.3 m

Angle is 88.3 degree from +X axis.

Explanation:

A = 550 m north

B = 500 m north east

C = 450 m north west

Write in the vector form

A = 550 j

B = 500 (cos 45 i + sin 45 j ) = 353.6 i + 353.6 j

C = 450 ( - cos 45 i + sin 45 j ) = - 318.2 i + 318.2 j

Net displacement is given by

R = (353.6 - 318.2) i + (550 + 353.6 + 318.2) j

R = 35.4 i + 1221.8 j

The magnitude is

[tex]R = \sqrt{35.4^{2}+1221.8^{2}}R = 1222.3 m[/tex]

The direction is given by

[tex]tan\theta =\frac{1221.8}{35.4}\\\\\theta = 88.3^{o}[/tex]

Answer:

36.11 degrees

Explanation:

index of refraction n = sin i/sinr

i is the angle of incidence

r is the angle of refraction

Substitute into the expression

1.39 = sin55/sin(r)

1.39 = 0.8191/sin(r)

sin(r) = 0.8191/1.39

sin(r) = 0.5893

r = arcsin(0.5893)

r = 36.11

hence the angle of refraction of light is 36.11 degrees