Answer:
Elements in the same group have the same number of valence electrons.
When moving right across a period, the valence electrons of the main group elements increase by one.
When moving down a group, the valence electrons of the main group elements increase by one.
Elements in the same period have the same number of valence electrons.
Elements in the same period of the periodic table have valence electrons in the same energy levels.
When elements are in the same period on the periodic table, it means that they have the same number of shells.
The energy level of valence electrons in a atom depends on how far it is from the nucleus. This means that:
Valence electrons on elements in the same period will be the same distance from their nucleus They will have the same energy level as they are equally attracted to their nucleusFor instance, Boron, Carbon and Nitrogen will have valence electrons in the same energy levels.
In conclusion, elements in the same period will have valence electrons in the same energy levels.
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differniate between Magnetic force and electrostatic force
Answer:
magnetic force:
i) It is exerted by a magnet.
ii)Magnetic forces are always normal to the direction of the velocity of the charge it acts upon.
Electrostatic force
i) It is exerted by electrically charged body.
ii)Electric force are independent of the direction the charge moves in.
✌✌✌✌
Our Moon a. was a separate small planet before it was captured by the Earth's gravity. b. spun off the fast-spinning Earth during the early formation of the Solar System. c. coalesced from gas and dust in its current place next to the Earth. d. was formed by the collision of the Earth with a Mars-sized protoplanet.
Answer:
d. was formed by the collision of the Earth with a Mars-sized protoplanet.
According to the The giant-impact hypothesis the Moon was formed from the debris of a collision between the Earth and a Mars-sized protoplanet.
is there any machine that is 100% efficient? why?why not
Answer:
No, it's not there.
Explanation:
For a machine to be 100% efficient, it has to be with an output which is equal to its input. But machines have an out put less than an input, hence efficiency below 100%.
difference between uniform motion and non uniform motion
Answer:
Uniform motion is a type of motion that is characterized as the motion of an object wherein the object moves in a straight line and its velocity remains unchanged along that line, regardless of the duration of time, as it occupies equal distances at equal time interval and Non-uniform motion is described as the motion of an object wherein the object moves at different speeds and does not cover the same distance at equal time intervals, regardless of the duration of the time interval.
Answer:
hope it's help you
Explanation:
In Uniform motion, the movement of a body is along the straight line with constant speed. In non uniform motion, the movement of a body is along the straight line with variable speed. In uniform motion, the body covers equal distance in an equal interval of time.
A bike travels at 3.0 m/s, and then accelerates to a speed of
8.5 m/s in a time of 2.5 seconds. The average acceleration of
the bike is
m/s2
The average acceleration of the bike is 2.2 m/s²
What is average acceleration?Acceleration, rate at which velocity changes with time, in terms of both speed and direction.
A point or an object moving in a straight line is accelerated if it speeds up or slows down.
According to the question,
Given, initial velocity, u=3.0m/s and final velocity v=8.5 m/s
Time = 2.5 seconds
If a be the acceleration.
a = [tex]\frac{v-u}{t}[/tex]
a = [tex]\frac{8.5 - 3.0}{2.5s}[/tex]
⟹ a=2.2 m/s²
So, The average acceleration of the bike is 2.2 m/s²
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Robin fired a bullet of mass 100 gm from a gun of mass 5 kg. The bullet leaves the gun with a speed of 400 m/s. After penetrating 4 cm of a plank of 10 cm, the bullet loses one third of its initial velocity.
a. Calculate the backward velocity of the gun?
b. Can the bullet penetrate the plank of the wood completely? Explain mathematically.
please help
(a) The recoil or backward velocity of the gun is 8 m/s.
(b) The bullet cannot penetrate the plank of the wood completely.
The given parameters include;
mass of the bullet, m₁ = 100 g = 0.1 kgmass of the gun, m₂ = 5 kginitial velocity of the bullet, u₁ = 400 m/sthickness of the plank, x = 10 cm(a) The backward or recoil velocity of the gun is calculated by applying the principle of conservation of linear momentum.
let the backward or recoil velocity of the gun = u₂m₁u₁ + m₂u₂ = 0
m₂u₂ = -m₁u₁
[tex]u_2 = -\frac{m_1u_1}{m_2} \\\\u_2 = - \frac{0.1 \times 400}{5} \\\\u_2 = -8 \ m/s[/tex]
Thus, the recoil or backward velocity of the gun is 8 m/s.
(b) determine if the bullet can penetrate the plank of the wood completely
the bullet traveled 4 cm and lost ¹/₃ of u₁the remaining distance to completely penetrate the plank = 6 cmthe final velocity of the bullet at 4 cm, v = 400 - ¹/₃ x 400 m/s = 266.67 m/sthe acceleration of the bullet is calculated as;
v² = u₁² + 2as
2as = v² - u²
[tex]a = \frac{v^2 -u_1^2}{2s} \\\\a = \frac{(266.67)^2 -(400)^2}{2\times 0.04} = -1.111 \times 10^6 \ m/s^2[/tex]
Finally, determine the distance traveled by the bullet when it comes to a complete stop, that is the final velocity = 0
[tex]v_f^2 = v^2 + 2ad\\\\2ad = v_f^2 - v^2\\\\d = \frac{v_f^2 - v^2}{2a} \\\\d = \frac{(0) - (266.67)^2}{2(-1.111\times 10^6)} \\\\d = 0.032 \ m[/tex]
d = 3.2 cm
The total distance traveled by the bullet inside the plank = 4 cm + 3.2 cm = 7.2 cm
Therefore, the bullet cannot penetrate the plank completely.
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mercury is commonly used in thermometer give reasons
Answer:
hi
BECAUSE MERCURY IS USED BECAUSE IT is the only liquid available in room temperatureExplanation:
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9. Which of the following is NOT a recommendation to help you succeed in this course?
Consistently and actively work in the course on a daily basis.
Wait until the end of the semester to complete all work.
Complete all assignments in a timely manner.
Contact your instructor if you have questions.
Answer:
Wait until the end of the semester to complete all work.
Explanation:
this is the obvious answer.
please mark me brainliest
Answer:
Wait until the end of the semester to complete all work
List two factors that compression force depends on
The magnitude (size or numerical value) and the direction.
Hope this helps!!! :)
Which of the following is a vector quantity? i. Force ii. Velocity iii. Acceleration iv. All of these 5771
Option ( iv ) is the correct answer.
☛ DefinitionA vector quantity the physical quantity that has both direction as well as magnitude.
what give negative acceleration ?
Answer:
But negative acceleration means that the rate of change of velocity is negative or velocity decreases. Example: (1) When we apply brakes in a moving car, then negative acceleration acts on it and the car stops. (2) When we throw a ball upwards, then also negative acceleration acts on it.
Explanation:
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MATHEMATICALLY A NEGATIVE ACCELERATION MEANS YOU WILL SUBTRACT FROM THE CURRENT VALUE OF THE VELOCITY.
what weight is recorded by a scale when it is placed inside a lift which is in free fall? Enplain.
Answer:
Explanation:
There is no pressure of your feet on the scales, and no pressure of the floor on the scales, so the scales will read zero*. Hence, your weight, in a freely falling lift is zero
during a journey, a car travels at 40 km in 2.5 hours, next 62 km in 3 hours, then took a break for 30 minutes, again travelled the last 120 km in 3.2 hours. calculate the average speed of the car during the journey.
Why does a ship float on water when it weighs about 100tones and why a stone of less than a kg sinks
Answer with Explanation:
Let me answer this in a simple way, since the density of stone is greater than that of water, the stone sinks as the weight of the stone is greater than the weight of water displaced by it. But the ship is designed in such a way that the relative density of the ship always becomes less than that of water. Therefore, the weight of the water displaced becomes equal to the total weight of the ship and thus it floats.
There are many other ways to explain this but this should give you the general idea.
The fluid inside the hydraulic jack has a pressure of 30,000 Pa. If the surface of
the piston that is used to lift an object is 0.1 m’in area, how much weight can
the jack lift?
Explanation:
p = F /A
F = P×A
F = 30,000 Pa / 0.1 m²
F = 300,000 N
thin wires have high resistance whereas thick wires have low resistance why???
can anyone say answer of this ^_^
Answer:
The resistance of a thin wire is greater than the resistance of a thick wire because a thin wire has fewer electrons to carry the current. The relationship between resistance and the area of the cross section of a wire is inversely proportional .
The best way to think about this is:
A thick/wide road, with many lanes, can carry more cars than a thin/narrow road, with only one or two lanes.
Define measurement with 10 points
Answer:
the process of comparing unknown quantities with known standards quantities are known as measurement
express in standard form
(I)0.000038
Answer:
3.8 x 10^-5
Explanation:
all you doing is putting it in the standard form I hope this help
define electrical resistance in a metal conductor
Answer:
Resistance is defined as the property of a conductor to resist the flow of charges through it. The resistance of conductor is numerically given as the ratio of potential difference across its length to the current flowing through it.
Explanation:
Answer the following questions 1 What is the difference between mass and weight of an object. Will the mass and weight of an object on the earth be same as their values on Mars ? Why?
Answer:
difference between mass and weight is that mass is amount of matter in a material while weight is a measure of how the force of gravity acts upon that mass.the mass of an object will be same on earth and mars but its weight on both planets will be different.
state the advantages and disadvantages of alkaline battery over a lead acid accumulator
Answer:
Alkaline batteries have longer shelf life than other batteries of the chloride type electrolyte batteries. They have a much higher energy density compared with other batteries. This allows the battery to produce the same energy while lasting longer than other batteries.
Advantage
1) Alkaline battery lasts long than other batteries
2) It have a much higher energy density
Disadvantage :
1) They are heavier and bulkier
2) They have high internal resistance
What is alkaline battery ?An alkaline battery is a type of primary battery that derives its energy from the reaction between zinc metal and manganese dioxide.
Advantage
Alkaline battery can produce same amount of energy by lasting longer than other batteries as it have longer shelf life than lead acid accumulator
Alkaline battery have a much higher energy density compared to lead acid accumulator
Disadvantage :
Alkaline battery are heavier and bulkier
Alkaline battery have high internal resistance
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what is required for force to come into play
Answer:
An interaction of one object with another object results in a force between the two objects. Thus, at-least two objects must interact for a force to come into play.
the slope of a line on a position vs time graph is the
a. velocity
b. time
c. distance
d. displacement
It's the velocity, but only the magnitude. It can't show the direction of the velocity. So it's better to call it speed.
a teacher drives from school to the mall. then she goes to the doctors office for a physical examination. what is the magnitude of her displacement
The magnitude of the teachers displacement is the difference between
the location of the school and the location of the doctors office
The reason behind the above expression are explained as follows
The known locations of the teacher;
Initial location; The school
Second location; The mall
The eventual location; The doctors office
The required information;
The magnitude of the teachers displacement
The method of obtaining the displacement of the teacher;
Qualitatively, the displacement of the teacher can be obtained by applying the definition of displacement as follows;
The definition of displacement is an object's change in position, given by the difference between its start and finish locations
According to the definition of displacement, therefore, the magnitude of
the teachers displacement is the distance between the school and the
doctors office which is given by the difference between the coordinates of
the location of the school and the location of the doctors office
The magnitude of the displacement of the teacher = The coordinate of the location of the doctors office - The coordinate of the location of the school
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A 4000 N force acts on an object that initially has a momentum of 400 kg-m/s for 0.9 seconds. What is the final momentum of the system?
Answer:
4360 Kgm/s
Explanation:
Applying,
Ft = M-M'................. Equation 1
Where F = force, t = time, M = Final momentum, M' = Initial momentum.
make M the subject of the equation
M = Ft+M'............ Equation 2
From the question,
Given: F = 4000 N, t = 0.9 seconds, M' = 400 kg-m/s
Substitute these values into equation 2
M = 4000+(0.9×400)
M = 4000+360
M = 4360 kgm/s
Hence the final momentum is 4360 kgm/s
A group of students are designing a field study to investigate the length of time a traffic light remains yellow.
Answer:
3 to 7 seconds.
Explanation:
According to the traffic engineers the length or the duration of the signal to turn form yellow or amber to green is more than 5 seconds. A time interval is needed to easy out the traffic flow.a sphere of diameter 6.0
cm is moulded into a thin wire of diameter 0.2 mm calculate the length of the wire in metres
Answer:
V1 = 4/3 pi R^3 = pi D^3 / 6 D = 2 R volume of sphere
V2 = pi r^2 L = pi d^2 L / 4 volume of wire
V2 / V1 = 1 = 3/2 d^2 L / D^3 since volumes are equal
L = 2/3 D^3 / d^2 = 2/3 * 6^3 / .02^2 = 360,00 cm = 3600 m
which two phenomena make up electromagnetism?
A) moving charges in an electric current attract each other
B) permanent magnets form a magnetic field from one pole to the other pole
C) an electric current causes a magnetic field around a core of magnetic metal
D) a moving magnet causes an electric current in a magnetic metal
Explanation:
the correct answer is option ( C ) and ( D )
Given: F = k· m. g
Solve for "k"
Answer:
[tex]F = kmg \\ k = \frac{F}{mg} [/tex]
Explanation:
F = k . m . g
=> F = k . mg
[tex] = > k = \frac{F}{mg} (ans)[/tex]
factor that affect gravitation
1) Two major factors, mass and distance, affect the strength of gravitational force on an object.
2) Most common factors that affect gravity are mass of the body, distance from centers, shape of bodies,etc. Gravity is a binding force, always acting to bind any material closure and closure inwards. If we think this way, then gravity is maximum at its centre and decreases slowly away from its centre.
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