Do you think, are we need to learn Measurement in Physics. Explain how the measurement is necessary and inevitable in real life situations?

Answer:

The hotter star radiates 625 times more energy per second from each square meter of its surface

Explanation:

Temperature of the hotter star is 30000 K

temperature of the cooler star = 6000 K

From Stefan-Boltzmann radiation laws, for a non black body

P = εσA[tex]T^{4}[/tex]

where

P is the energy per second or power of radiation

ε is the emissivity of the body

σ is the Stefan-Boltzmann constant of proportionality

A is the area of the sun

T is the temperature of the sun

The sun can be approximated as a black body, and the equation reduces to

P = σA[tex]T^{4}[/tex]

For the hotter body,

P = σA([tex]30000^{4}[/tex]) = 8.1 x 10^17σA  J/s

For the cooler body,

P = σA([tex]6000^{4}[/tex]) = 1.296 x 10^15σA   J/s

comparing the two stars energy

==> (8.1 x 10^17)/(1.296 x 10^15) = 625

This means that the hotter star radiates 625 times more energy per second from each square meter of its surface

Answer:

   f = 6.37 Hz,       T = 0.157 s

Explanation:

The expression you have is

       y = 5 sin (3x - 40t)

this is the equation of a traveling wave, the general form of the expression is

      y = A sin (kx - wt)

where A is the amplitude of the motion, k the wave vector and w the angular velocity

Angle velocity and frequency are related

         w = 2π f

         f = w / 2π

from the equation w = 40 rad / s

        f = 40 / 2π

        f = 6.37 Hz

frequency and period are related

       f = 1 / T

       T = 1 / f

       T = 1 / 6.37

       T = 0.157 s

Answer:

Explanation:

Solution,

When a certain object comes in motion from rest, in the case, initial velocity = 0 m/s

Initial velocity ( u ) = 0 m/s

Final velocity ( v ) = 72 km/h ( Given)

We have to convert 72 km /h in m/s

[tex]72 \: km \: per \: hour[/tex]

[tex] = 72 \times \frac{1000}{60 \times 60} [/tex]

[tex] = 20 [/tex] m/s

Final velocity ( v ) = 20 m/s

Time taken ( t ) = 2 seconds

Acceleration (a) = ?

Now,

we have,

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

[tex]a = \frac{20 - 0}{2} [/tex]

[tex]a = \frac{20}{2} [/tex]

[tex]a = 10 [/tex] m/s ^2

Hope this helps...

Good luck on your assignment..

Answer:

C 80 m

Explanation:

Given:

v₀ = 30 m/s

a = -10 m/s²

t = 8 s

Find: Δy

Δy = v₀ t + ½ at²

Δy = (30 m/s) (8 s) + ½ (-10 m/s²) (8 s)²

Δy = -80 m

The ball lands 80 m below where it started.  So the height of the cliff is 80 m.

Answer:

Explanation:

Friction causes generation of heat and causes increased wear and tear.

The friction is a resistive force and is related to heat energy, so an increase in friction results in the generation of heat, so option D is correct.

Two solid objects cannot roll or slide over one another due to the force of friction. Although frictional forces can be useful, such as the traction needed to walk without slipping, they can also present a large degree of resistance to motion. Automobile engines need about 20% of their power to overcome frictional forces in moving parts.

The fundamental source of friction between metals appears to be the adhesion forces between the contact zones of the surfaces, which are always microscopically uneven. Friction is produced by shearing, these "welded" seams, and the rubbing action of the rougher, tougher surface against the softer, smoother surface.

The friction is a resistive force trying to oppose the force applied As friction is related to heat when we increase the heat, the friction increases, and vice versa.

To know more about Friction:

https://brainly.com/question/28356847

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Answer:

A.A

Explanation:

The balls usually bounce 60% of the original height because it stores 60% of the energy it had before the bounce. When a ball is dropped from a great height it has kinetic energy before it hits the ground which is the result of the bounce of ball. The size of ball does matter in this case, Large balls will bounce higher.

Answer:

462000J

Explanation:

Quantity of heat= mass x specific heat capacity of iron x change in temp

specific heat capacity of iron is 462J/Kg/K

change in temp = 250-50= 200°C

200°C is equivalent to 200K since 1°C is 1K

Q= mct

= 5x462x200

= 462000J

Answer:

3 m/s²

Explanation:

Sum of forces in the x direction:

∑F = ma

68 N − 23 N = (15 kg) a

a = 3 m/s²

Answer:

Translatory Motion:

The motion of a body along a line is called Translatory Motion. The line may be straight or curved. There are three types:

1) Linear Motion:

Straight line motion of a body is called Linear Motion.

E.g. Movement of a car on a straight road.

2) Circular Motion:

Motion of a body along a circle is called circular motion.

E.g. Movement of a toy train along its circular track.

3) Random Motion:

The irregular motion of a body is called random motion.

E.g. Movement of a bee.

.......Hope it helps :)........

Answer:

a. 2 Hz b. 0.5 cycles c . 0 V

Explanation:

a. What is period of armature?

Since it takes the armature 30 seconds to complete 60 cycles, and frequency f = number of cycles/ time = 60 cycles/ 30 s = 2 cycles/ s = 2 Hz

b. How many cycles are completed in T/2 sec?

The period, T = 1/f = 1/2 Hz = 0.5 s.

So, it takes 0.5 s to complete 1 cycles. At t = T/2 = 0.5/2 = 0.25 s,

Since it takes 0.5 s to complete 1 cycle, then the number of cycles it completes in 0.25 s is 0.25/0.5 = 0.5 cycles.

c. What is the maximum emf produced when the armature completes 180° rotation?

Since the emf E = E₀sinθ and when θ = 180°, sinθ = sin180° = 0

E = E₀ × 0 = 0

E = 0

So, at 180° rotation, the maximum emf produced is 0 V.

Answer:

The correct answer is "0.246".

Explanation:

Given that the amplitude is decreased by a factor of 9, then

[tex]A \rightarrow (A-\frac{A}{9} )[/tex]

[tex]A \rightarrow \frac{8A}{9}[/tex]

As we know,

Energy will be:

⇒  [tex]E_{1}=\frac{1}{2}KA^2[/tex]

and,

⇒  [tex]E_{2}=\frac{1}{2}K(\frac{8A}{9} )^2[/tex]

          [tex]=\frac{64KA^2}{162}[/tex]

⇒  [tex]\Delta E=E_1-E_2[/tex]

On putting the estimated values, we get

           [tex]=\frac{1}{2}KA^2-\frac{64KA^2}{162}[/tex]

⇒  [tex]\frac{\Delta E}{E}=\frac{\frac{20}{162}KA^2}{\frac{1}{2}KA^2}[/tex]

          [tex]=\frac{40}{162}[/tex]

          [tex]=0.246[/tex]

Answer:

*  most of the emission would be in the infrared part, the visible radiation would be very small.

*total intensity of the semition decreases that the intensity depends on the fourth power of the temperature

Explanation:

The radiation emitted by the Sun is approximately the radiation of a black body, if the Sun were to cool, the maximum emission wavelength changes

          λ T = 2,898 10⁻³

          λ = 2,898 10⁻³ / T

if the temperature decreases the maximum wavelength the greater values ​​are moved, that is to say towards the infrared. Therefore the emission curve also moves, in this case most of the emission would be in the infrared part, the visible radiation would be very small.

Furthermore, the total intensity of the semition decreases that the intensity depends on the fourth power of the temperature according to Stefan's law

           P = σ A eT⁴

Answer:

1.125x10^-10 electrons

Explanation:

Pls see attached file

Answer:

a. q = qm/√2 b. qm/√(2LC)

Explanation:

a. Charge on the capacitor

Let U₁ = energy in inductor and U₂ = energy in capacitor and U = total energy in circuit.

So, U₁ + U₂ = U.

Since the energy is shared equally between the capacitor and inductor, U₁= U₂,so

2U₂ = U

and U₂ = U/2

Now U₂ = q²/2C where q is the charge on the capacitor with capacitance C and

U = (qm)²/2C where qm is the maximum charge on the capacitor.

Since U₂ = U/2,

Substituting the values for U₂ and U, we have

q²/2C = [(qm)²/2C]/2

q² = (qm)²/2

taking square-root of both sides, we have

q = qm/√2

b. The current in the inductor

Since the energy in the capacitor equals the energy in the inductor,

1/2LI² = 1/2q²/C where L is the inductance of the inductor and I the current through it.

I² = q²/LC

taking square-root of both sides, we have

I = q/√LC

substituting the value of q from above, we have

I = qm/√2 ÷ √LC

I = qm/√(2LC)

Answer:

cluttered

Explanation:

The correct word to describe the garage would be cluttered.

A place is said to be cluttered when it is filled with an untidy collection of material things. In this case, the garage is filled with materials such as bike wrenches, tires, frames, etc.

Inviting can also mean tempting, attractive, etc, and has no relevance to the condition of the garage as described in the excerpt.

Dangerous can also mean harmful, and not the right word to describe the garage.

Sparse can also mean scanty, scattered, and would be the opposite of the condition of the garage.

Correct answer: cluttered

Answer:

c.  cluttered

Explanation:

Answer:

Los datos que tenemos:

Rapidez: 69km/h

Tiempo que tarda en frenar = 4s.

Distancia inicial entre la tracto-mula y la vaca = 25m

Ok, la ecuación de desaceleración es:

D = (sf - si)/t

sf = velocidad final = 0m/s

si = velocidad inicial = 69km/h

t = tiempo = 4s

D = -69km/h/4s

ok, 1h = 3600s

D = (-69km/s)*1/(4*3600s)  = -0.0048 km/s^2

Entonces la ecuación de aceleración es:

a(t) =  -0.0048 km/s^2

Para la velocidad, integramos sobre el tiempo

v(t) = (-0.0048 km/s^2)*t + v0

donde v0 es la velocidad inicial, en este caso v0 = 69km/3600s = 0.0191km/s  

v(t) =  (-0.0048 km/s^2)*t + 0.0191km/s

Para la posición volvemos a integrar sobre el tiempo, esta vez suponemos la posición inicial igual a cero.

p(t) = (1/2)*(-0.0048 km/s^2)*t^2 + 0.0191m/s*t

Ahora, si p(t=4s) < 25m, esto implica que la tracto-mula no impacto con la vaca.

p(4s) = (1/2)*(-0.0048 km/s^2)*(4s)^2 + 0.0191km/s*4s = 0.038km

y 1km = 1000m

0.038km = 0.038*1000m = 38m

Entonces si, atropello a la vaca.

Answer:

greatest displacement = 44.1m

initial velocity= 29.4m/s

Explanation:

Greatest displacement

s=1/2at^2

= (9.8/2 ×9)m

= 44.1m

initial velocity

s=ut-1/2at^2

44.1= 3u -(1/2×9.8×9)

44.1=3u-44.1

3u=88.2

u=29.4m/s

Answer:

Explanation:

In this problem we are required to find the potential energy possessed by the television

Given data

mass of television m = 15 kg

height  added above the ground, h= 1-0.3 = 0.7 m

acceleration due to gravity g = 9.81 m/s^2

apply the formula for potential energy we have

P.E= m*g*h

P.E = 15*9.81*0.7 = 103 Joules

Answer:

acceleration is the rate of change of the velocity of an object with respect to time. Accelerations are vector quantities. The orientation of an object's acceleration is given by the orientation of the net force acting on that object.

Explanation:

Calculating acceleration involves dividing velocity by time — or in terms of SI units, dividing the meter per second [m/s] by the second [s]. Dividing distance by time twice is the same as dividing distance by the square of time. Thus the SI unit of acceleration is the meter per second squared .

Answer:

You should still workout 90 min.

The proper time is measured by a single clock in a single place.

The proper time on earth is 90 min.

The clock on the rocket is also in a single place in the frame of the rocket so you still need to workout for 90 min.

Answer:

d) harvesting and threshing both.

Explanation:

Hope it helps you...

Answer:

d. She will be slightly lower than you but moving upward toward you.

Explanation:

Since your swing is slightly shorter than your friend's swing, then you will have more angular speed than your friend. Angular speed increases with a decrease in radius. The closer the body is to the center, the faster the body swings. By the time you would have completed one complete swing back and forth, your friend will just be moving towards you, and she will be slightly lower than you but moving upwards towards you. This principle is the same reason gymnasts pull their limbs closer to their body when they need to swing faster.

Answer:

Explanation:

just use the gravational force equation which is G x m of earth x m of object divided by r squared (which is radius of earth)

Answer:

625 cm²

Explanation:

The pressure is the same on both pistons.

F/A = F/A

200 N / 25 cm² = 5000 N / A

A = 625 cm²

When a snowball turns into a puddle of water, we know that (the snow ball gains energy and changes from a solid to liquid).

This is correct due to the fact that particles of the snowball are gaining speed and so it is heating up, when the solid's temperature reaches the melting point, it will become a liquid.

Therefore, D is the correct answer.

Answer:

0.252 m/s

Explanation:

Applying the law of conservation of momentum,

Total momentum before collision = Total momentum after collision

Note: From the question, The collision between the car and the train is an inelastic collision and as such, both move with a common velocity after collision.

mu+m'u' = V(m+m')................... Equation 1

Where m = mass of the train, u' = initial velocity of the train, m' = mass of the car, u' = initial velocity of the car, V = common velocity after collision.

make V the subject of the equation

V = (mu+m'u')/(m+m')............... Equation 2

Given: m = 270000 kg, u = 0.325 m/s, m' = 52500 kg, u' = -0.12 m/s

Substitute these values into equation 2

V = [(270000×0.325)+{52500(-0.12)}]/(270000+52500)

V = 81450/322500

V = 0.252 m/s

Answer: 14000 N

Explanation: i just did it on khan academy

Answer:

The equivalent or total resistance of the circuit is 6

Explanation:

6 &6 are in series

6+6=r

r= 12

1/Rtotal= 1/12+1/2

1/Rt=2/12=1/6

Rt=6

Here's the neat, cool way to convert units like this:

-- 1 kilogram  =  1,000 grams

-- 1 meter  =  100 centimeters

So . . . . .

(1000 kg/m³) x (1000 g/kg) x (1 m/100 cm)³ =

(1,000 kg/m³) x (1,000 g/kg) x (1 m³/1,000,000 cm³) =

(1,000 x 1,000 x 1 / 1,000,000) (kg-g-m³ / m³-kg-cm³)  =  1 g/cm³