(Q020) Stars a. all explode cataclysmically when they die and contribute their matter to future star generations. b. begin as protostars, which fire up when they collapse and become denser and hotter. c. have unlimited amounts of fuel and therefore exist indefinitely. d. create elements by splitting the nuclei of small atoms into the nuclei of larger atoms.

Answer:

1. b

2. e

3. a

4. c

5. d

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Supplied energy=300kJ

Used energy:-

[tex]\\ \sf\longmapsto 300-70.5=229.5kJ[/tex]

We know

[tex]\boxed{\sf Efficiency=\dfrac{Used\:Energy}{Supplied\:Energy}\times 100}[/tex]

[tex]\\ \sf\longmapsto Efficiency=\dfrac{229.5}{300}\times 100[/tex]

[tex]\\ \sf\longmapsto Efficiency=\dfrac{229.5}{3}[/tex]

[tex]\\ \sf\longmapsto Efficiency=76.5\%[/tex]

The overall efficiency of the electric car = 76.5 %

To find the efficiency the given values are:

Energy supplied = 300 kJ

Energy wasted = 70.5 kJ

      In the system the output energy is compared to the input energy is known as efficiency. That can be written as percentage ratio of output energy to the input energy.

Formula of efficiency is,

             Efficiency = ( E out / E in ) × 100

Here, Energy supplied = 300 kJ

so, energy used = Energy supplied - Energy wasted

                           = 300 - 70.5

                           =  229.5 kJ

Thus, substituting E out = 300 kJ , E in = 229.5 kJ

            Efficiency = ( 229.5 / 300 ) ×100

                             = 229.5 / 3

                             = 76.5

Hence, The overall efficiency of the electric car is 76.5 %

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Answer:

Standard weight: We calculate the standard weight as follows: G = L * mweight, where L is the length of the beam calculated as the difference between the extreme points of the beam body along the direction of the beam axis, taking into account all features except holes.

Explanation:

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Answer

Explanation:

Convert the time to seconds = 0.6 × 60 × 60

= 2160seconds

Velocity = distance ÷ time

Velocity = 500 ÷ 2160

Velocity = 0.23meters per seconds(m/s)

Acceleration = Velocity ÷ time

Acceleration = 0.23 ÷ 2160

Acceleration = 0.000106meters per seconds ²(m/s²)

Answer:

option C

Explanation:

Final velocity of the object is 114 m / s. Hence, final velocity of the object is 114 m / s.

Answer:

A ball rolls off the table and free falls to the ground. Which statement accurately describes its acceleration? Its acceleration is downward but remains a constant value as it falls.

Answer:

(a) 11.3 T

(b) 6.09 T

Explanation:

Current, I = 14 kA = 14000 A

number of turns, N = 900

inner radius, r = 0.7 m

outer radius, R = 1.3 m

The magnetic field due to a circular coil is given by

[tex]B = \frac{\mu o}{4\pi}\times \frac{2 N\pi I}{R}[/tex]

(a) The magnetic field due to the inner radius is

[tex]B = 10^{-7}\times \frac{2\times 900\times 3.14\times 14000}{0.7}\\\\B = 11.3 T[/tex]

(b) The magnetic field due to the outer radius is

[tex]B = 10^{-7}\times \frac{2\times 900\times 3.14\times 14000}{1.3}\\\\B = 6.09 T[/tex]

Answer:

The word ‘radiation’ is used to describe particles or waves that are emitted by an object  

In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium. This includes: electromagnetic radiation, such as radio waves, microwaves, infrared, visible light, ultraviolet, x-rays, and gamma radiation (γ)

Explanation:

There are four major types of radiation: alpha, beta, neutrons, and electromagnetic waves such as gamma rays. They differ in mass, energy and how deeply they penetrate people and objects.

The first is an alpha particle. These particles consist of two protons and two neutrons and are the heaviest type of radiation particle. Many of the naturally occurring radioactive materials in the earth, like uranium and thorium, emit alpha particles

The second kind of radiation is a beta particle. It's an electron that is not attached to an atom. It has a small mass and a negative charge. Tritium, which is produced by cosmic radiation in the atmosphere and exists all around us, emits beta radiation. Carbon-14, used in carbon-dating of fossils and other artifacts, also emits beta particles. Carbon-dating simply makes use of the fact that carbon-14 is radioactive. If you measure the beta particles, it tells you how much carbon-14 is left in the fossil, which allows you to calculate how long ago the organism was alive.

The third is a neutron. This is a particle that doesn't have any charge and is present in the nucleus of an atom. Neutrons are commonly seen when uranium atoms split, or fission, in a nuclear reactor. If it wasn't for the neutrons, you wouldn't be able to sustain the nuclear reaction used to generate power.

The last kind of radiation is electromagnetic radiation, like X-rays and gamma rays. They are probably the most familiar type of radiation because they are used widely in medical treatments. These rays are like sunlight, except they have more energy. Unlike the other kinds of radiation, there is no mass or charge. The amount of energy can range from very low, like in dental x-rays, to the very high levels seen in irradiators used to sterilize medical equipment.

Explanation:

The answer is mentioned above.

Hope it helps.

Answer:

78.34

Explanation:

1.3/30=78.3m

Answer:

To summarize, an object moving in uniform circular motion is moving around the perimeter of the circle with a constant speed. While the speed of the object is constant, its velocity is changing. Velocity, being a vector, has a constant magnitude but a changing direction.

Explanation:

Speed refers to how fast an object is moving. It can be thought of as the rate at which an object covers distance.

Velocity refers to the rate at which an object changes its position. If you picture a person moving rapidly - one step forward and one step back- always returning to the original starting position, the speed is very rapid, but the velocity is zero. Because the person always returns to the original position, this motion would bébé result in a change in position. Since velocity is defined as the rate at which the position changes, this motion results in zero velocity. To maximize velocity, every effort must be made to maximize the amount an object is displaced from its original position. Every movement should be moving the object further from where it started. Velocity is DIRECTION AWARE. When evaluating the velocity of an object, you have to keep track of direction. This is one of the essential differences between speed and velocity: speed does not keep track of direction, while velocity is directionally aware.

So, when the moon moves around the Earth, the speed remains constant, but since it's moving in an elliptical orbit, it's direction is constantly changing.

Answer:

334m/s

Explanation:

If you take the data you gave and insert it into the equation f=v/λ the frequency would come out to be 3.34m

334 m/s is  the Velocity of sound in air.

Wave velocity in common usage refers to speed, although, properly, velocity implies both speed and direction.

The velocity of a wave is equal to the product of its wavelength and frequency (number of vibrations per second) and is independent of its intensity.

Mathematically , v=fλ

According to the question,

Sound frequency (f)  = 100Hz

Wavelength (λ)= 3.34m

Computing the values in the formula,

v=fλ

v = 100Hz x 3.34m

v= 334m/s

Therefore,

Velocity of sound in air is 334 m/s.

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F = m · g

m = 1485 kg

g = 10 N/kg

F = 1485 kg · 10 N/kg = 14 850 N = 14,85 kN

Answer: The weight on Earth is 14,85 kN.

Answer:

Gravitational force will be 16 times more.

Explanation:

we know;

Gravitational force (F) = (Gm1m2)/d^2

when mass of each is doubled and distance between them is halved;

F= (G2m1×2m2)/(d/2)^2

=(4Gm1m2)/(d^2/4)

=4×4(Gm1m2)/d^2

=16(Gm1m2)/d^2

=16F

Answer:

i. The pressure of due to the water, P, is given according to the following equation;

P = ρ·g·h

Where;

ρ = The density of the water (a constant) = 997 kg/m³

g = The acceleration due to gravity = 9.81 m/s²

h = The height of the water (minimum h = h₁, maximum h = h₂)

The pressure is directly proportional to the water height, and we have;

The pressure, P, will be maximum when the water height, h, is maximum or h = h₂, which is the level DC

ii. The thrust = The force acting on the body = Pressure × Area

The maximum areas exposed to the water are on side AB and DC

However, the pressure at level DC, which is the location of the maximum pressure, is larger than the pressure at level AB, therefore, the maximum thrust will be at the level DC

Explanation:

Answer:

m_2 = 2600kg

Explanation:

P_1 = P_2

P = (m_1)*(v_1)+(m_2)(v_2)

P_1 = (3250kg)(8.1m/s)+(m_2)(0m/s)

P_1 = 26,325 kg*m/s

P_2 = (3250kg)(4.5m/s)+(m_2)(4.5m/s)

P_2 = 14,625kg*m/s+(4.5m/s)m_2

26,325 kg*m/s = 14,625kg*m/s+(4.5m/s)m_2

11,700kg*m/s = (4.5m/s)m_2

m_2 = 2600kg

Answer:

in order to know the length of something

Answer:

Reflection is simply the property of a light that rebounds or bounces back after hitting a surface.

Refraction is when the light, which passes through a surface, undergoes some changes in appearance whenever it usually passes through a medium.

Explanation:

It doesn't depends upon other.

It have it's own identity.

It's a lot easier to measure temperature than to measure the motion of component particles.

Answer:

The right hand rule states that, to find the direction of the magnetic force on a positive moving charge, the thumb of the right hand point in the direction of v, the fingers in the direction of B, and the force (F) is directed perpendicular to the right hand palm.

Explanation:

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Answer:

Answer in photo

Explanation:

Answer in photo

One of the scientist's jobs is to report the results of his experiments to all the other scientists in the world.

There isn't a single real science shop anywhere in the world that uses the US customary system of units. Not one.

Even in the measly three countries that use it for measuring carpet, pumping gas, and weighing fish ... Myanmar, Liberia, an the USA ... the scientists do their work in the SI/MKS/metric system.

Answer:

88 m ^2

Explanation:

Answer:

0 Newtons

Explanation:

The velocity of the object does not change, it is a constant 54 km/hr. When velocity does not change, acceleration is zero. Using the formula Force = mass x acceleration, we find:

mass = 1200 kg

acceleration = 0

F  = (1200)(0) = 0

12. C

13. A

14. B

15. D

16. D

17. B

We have that the time, to the nearest minute, when the water level is at 1.125 m for the second time after midnight is

[tex]t=10.0hours[/tex]

From the Question we are told that

Maximum height [tex]h_{max}=3m[/tex]

Minimum height  [tex]H_{min}=0.5m[/tex]

Time for  next high tide will occur[tex]T=12 hours =>720 min[/tex]

Generally Average Height

[tex]h_{avg}=\frac{3+0.5}{2}\\\\h_{avg}=1.75[/tex]

Therefore determine Amplitude to be

[tex]A=h_{max}=j_{avg}\\\\A=3-1.75\\\\A=1.25[/tex]

Generally, the equation for Time is mathematically given by

At t=0

[tex]h(x)=Acos(Bx)+h_{avg}[/tex]

Where

[tex]B=\frac{2\pi}{P}\\\\B=\frac{2\pi}{720}\\\\B=8.73*10^{-3}[/tex]

Therefore

[tex]h(t)=Acos8.73*10^{-3}(t)+h_{avg}[/tex]

Hence the Time at [tex]T=1.125[/tex] is

[tex]1.125(t)=1.25cos(8.73*10^{-3})(t)+1.75[/tex]

[tex]-0.1249t=1.75[/tex]

[tex]t=10.0hours[/tex]

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Answer:

[tex]X=3.37561*10^{-16}[/tex]

Explanation:

From the question we are told that:

Width [tex]w=2.7m[/tex]

Acceleration [tex]a=9.8m/s^2[/tex]

Generally the equation for The apparent deflection is mathematically given by

X= 0.5 *g*t^2

Where

[tex]t=\frac{width}{Velocity of light}[/tex]

[tex]t=\frac{2.5}{3*10^8}[/tex]

[tex]t=8.3*10^{-9}[/tex]

Therefore

[tex]X= 0.5 *9.8*(8.3*10^{-9})^2[/tex]

[tex]X=3.37561*10^{-16}[/tex]