Answer:
B
Explanation:
the Halogen families have 7 valence electrons
Why is it difficult to maintain constant speed of a vehicle?
Answer:
The road surface is always rough, so the frictional force between the tires and the road surface make it difficult to maintain constant speed because acceleration always changes.
In----- theory, the actual wishes that are threatening to the dreamers conscious awareness are disguised
Answer:
Unconscious wish fulfillment
Explanation:
Unconscious wish fulfillment
(In the unconscious wish fulfillment theory, the actual wishes of the dreamer that are threatening to the dreamer's conscious awareness are disguised.)
A particular electric car is supplied with 300 kJ of chemical energy by the battery. Of this, a total of 70.5 kJ of energy is wasted as heat.
Calculate the overall efficiency of the electric car.
Supplied energy=300kJ
Wasted energy=70.5JUsed 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
Define efficiency and calculate the value of efficiency.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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The sky is blue because: Select one: a. the index of refraction for air is slightly larger for blue than for red b. atomic hydrogen is blue c. air molecules tend to polarize light along a horizontal axis d. oxygen and nitrogen molecules are small compared to the wavelengths of visible light e. oxygen molecules have a lower energy ground state than nitrogen molecules
Answer:
a. the index of refraction for air is slightly larger for blue than for red
A sound frequency 100Hz and wavelength 3.34m is travelling through air, calculate the Velocity of sound in air.
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.
What is the velocity of a wave?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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(d) Below shows a hydraulic press with a pump piston of area 4 cm2 and a ram area of
12 cm2 . IF A force of 300 N is applied on the pump piston, find:
(i)the maximum load on the ram.
(ii) the velocity ratio of the machine.
(iii) the mechanical advantage of the machine.
(iv)the efficiency of the machine.
Answer:
Explanation:
hi
An electron enters the magnetic field at right angle from left B into paper. The electron will be deflected?
Answer:
According to this direction of force is perpendicular to the direction of current and magnetic field. Therefore force is opposite to electron into the paper at 90°.
20. A semiconductor is a
crystalline solid that conducts current under any condition
metallic solid that conducts current under any condition
metallic solid that conducts current under certain conditions
crystalline solid that conducts current under certain conditions
Answer:
D. crystalline solid that conducts current under certain conditions
Explanation:
Semiconductors are crystalline solids that has the ability to conduct electrical currents but on certain conditions e.g heat. The conduction of semiconductors is less than that of conductors (metals) but more than insulators (nonmetals), hence, they are said to be intermediates of conductors and insulators in terms of electrical conductivity.
Examples of semiconductors are silicon, boron, carbon, germanium, arsenic etc.
HELP me
Which sentence best describes how the horse is doing work?
A It is using motion to transfer energy and force away from the heavy object
B it is using force to apply power and decrease the energy of the heavy object
C it is using energy to apply the force needed to move the object over a distance
D it is using power to force the heavy object to move over A certain distance
Which is an outer planet?
Answer:
pluto
Explanation:
Dwarf because it is very minut
Answer:
I think Saturn.
Explanation:
I think the inner planets are Mercury, Venus, Earth and Mars whereas the outer ones are Jupiter, Saturn, Uranus and Neptune.
an electron is moving at 3.6 x 10^3 m/s. a photon with what wavelength would have the same momentum????
Answer:
The wavelength of the photon that would have the same momentum as the electron is 202.2180996 nm
Explanation:
The velocity of the electron, v = 3.6 × 10³ m/s
The momentum of an electron, [tex]p_e[/tex] = m × v
Where;
v = The mass of the electron = 9.109 × 10⁻³¹ kg
∴ [tex]p_e[/tex] = 9.109 × 10⁻³¹ kg × 3.6 × 10³ m/s = 3.27924 × 10⁻²⁷ kg·m/s
According to the de Broglie equation, the momentum of a photon, p, is given as follows;
p = h/λ
Where;
h = 6.63 × 10⁻³⁴ J·s
λ = The wavelength of the photon
∴ λ = h/p
According to the question, we have;
p = [tex]p_e[/tex] = 3.27924 × 10⁻²⁷ kg·m/s
∴ λ = 6.63 × 10⁻³⁴ J·s/(3.27924 × 10⁻²⁷ kg·m/s) = 2.02180993 × 10⁻⁷ m
The wavelength of the photon, λ = 2.02180993 × 10⁻⁷ m = 202.2180993 × 10⁻⁹ m = 202.2180993 nm.
help with this physics question please :)
Answer:
is that rm in you profile pic
How can we measure electromotive force of a battery illustrated answer with the help of circuit diagram
Answer:
the emf of the cell can be determined by measuring the voltage across the cell using a voltmeter and the current in the circuit using an ammeter for various resistances.
give one example where friction is a hindrance.
Answer:
an example of when friction is a hindrance, is if someone with shorts is sliding down a slide. their skin rubbing on the slide will cause friction and will slow them down. another example is if you're dragging a large wooden box across the floor. the wood and the floor interacting cause friction and will make it more difficult to push the box.
Explanation:
hope this helps :D
A car has a mass of 2000 kg. While it is traveling along a perfectly flat road, it goes around an unbanked turn that has a radius of 40.0 m. The coefficient of static friction between the car tires and the road is 0.500. The car travels successfully around the turn at a constant speed of 10.0 m/s. Calculate the magnitude of the car's acceleration as it goes around the turn. _______ m/s^2
Answer:
2.5 m/s²
Explanation:
The given parameters are;
The mass of the car, m = 2,000 kg
The radius of the car, r = 40.0 m
The coefficient of friction between the car tires and the road, μ = 0.500
The constant speed with which the car moves, v = 10.0 m/s
The normal reaction of the road on the car, N = The weight of the car;
∴ N = m × g
Where;
g = The acceleration due to gravity ≈ 9.81 m/s²
N ≈ 2,000 kg × 9.81 m/s² = 19,620 N
The frictional force, [tex]F_f[/tex] = μ × N
The centripetal force, [tex]F_c[/tex] = m·v²/r
The car moves without slipping when [tex]F_f[/tex] = [tex]F_c[/tex]
Therefore, [tex]F_f[/tex] = 0.500 × 19,620 N = 2,000 kg × [tex]v_{max}[/tex]²/40.0 m
∴ [tex]v_{max}[/tex] = √(0.500 × 19,620 N × 40.0 m/2,000 kg) ≈ 14.007 m/s
Therefore, the velocity with which the car moves, v < [tex]v_{max}[/tex]
The cars centripetal acceleration, [tex]a_c[/tex] = v²/r
∴ [tex]a_c[/tex] = (10.0 m/s)²/40.0 m = 2.5 m/s²
The cars centripetal acceleration as it goes round the turn, [tex]a_c[/tex] = 2.5 m/s².
how do u calculate the kinetic energy of a ball of mass 0.25kg being kicked vertically upwards with a speed of 5m/s
Answer:
3.125J
Explanation:
K.E.= 1/2(mass)(velocity)^2
K.E.=1/2(0.25)(5)^2=3.125
.
What is the equation for work?
Work = force / distance
Work = force - distance
Work = force + distance
Work = force * distance
Answer:
Work = F X D
Explanation:
Work (J) equals Force (N) multiplied by Distance (M)
A cricketer throws a ball sideways with an initial velocity of 30 m/s. She releases the ball from a height of 1.3m. Calculate how far the ball travels before hitting the ground.
Answer:
78.34
Explanation:
1.3/30=78.3m
A variable is a letter that stands in for a number and unit... True or False?
Help me frfr I don’t understand
The points are
(1,10)
(6,0)
[tex]\boxed{\sf slope(m)=\dfrac{y_2-y_1}{x_2-x_1}}[/tex]
[tex]\\ \sf\longmapsto m=\dfrac{0-10}{6-1}[/tex]
[tex]\\ \sf\longmapsto m=\dfrac{-10}{5}[/tex]
[tex]\\ \sf\longmapsto m=-2[/tex]
Which type of reactions usually happens slowest?
Answer:
option b is correct..................
Why do scientists not use US customary units when reporting their data?
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.
An object moving north with an initial velocity of 14 m/s accelerates 5 m/s2 for 20 seconds. What is the final velocity of the object?
39 m/s
90 m/s
114 m/s
414 m/s
Answer:
option C
Explanation:
Final velocity of the object is 114 m / s. Hence, final velocity of the object is 114 m / s.
help me please i will mark as brainliest
Answer:
you would be paying $1845.26
Write down the role played by four digestive juices in digestion and the
organs which secrete them.
Answer:
Digestive juices secreted by various organs such as salivary glands in the mouth, stomach, liver and pancreas help in the process of digestion of food. Saliva secreted by the salivary glands in the mouth aids in the breakdown of starch present in the food to simple sugar
Explanation:
can someone please help me with a and b? what do they mean by amplitude?
Explanation:
first answer is that the to and fro movement of a pendulum is known as amplitude
what do you mean by scattering of light
Answer:
Scattering of light is the phenomenon in which light rays get deviated from its straight path on striking an obstacle like dust or gas molecules, water vapours etc. Scattering of light gives rise to many spectacular phenomena such as Tyndall effect and the “red hues of sunrise and sunset”.
importance of estimation in our lives
6.
For a given prism the angle of incidence is changed from 0° and 90', the angle of deviation [ ]
b) decreases
c) first decreases and then increases
d) first increases and then decreases
a) increases
Answer:
increase
Explanation:
please mark as brainlyest
Answer
A.Increses
Explanation:
please help urgent have you ever seen the old “Pull the tablecloth out from under the dishes” trick? Use Newton’s 1st Law to explain the following:
a. In this trick, are the dishes “objects in motion,” or “objects at rest?”
b. If the dishes end up staying on the table, was an UNBALANCED FORCE applied to them? How do you know?
Answer:
I kinda dont remember the 1st law so search it up on
and it should tell u , but if u need any help from the
