Class 9 SCIENCE
ch 2 Is matter around us pure
Question -
what you mean by crystallization? Give example.
Answer:
Crystallization is defined as a process by which a chemical is converted from a liquid solution into a solid crystalline state.
1.If a wooden cube has length and breadth of 1.5 m each and it is exerting a pressure of 1200 pa. What is it's weight (f)?
Explanation:
Explanation:
Pressure is defined as a Force over an
Area.
p=F/A
We can rearrange this to make the Force
the subject
F = p *A
The pressure is given as 1200 Pa.
We know a pascal is 1 Newton / Square
metre = N/m²
The area of a cube will be width * breadth
= 1.5 m * 1.5 m= 2.25 m²
So the force the cube is pushing down
with (its weight) is simply
F = p * A = 1200 N/m² * 2.25 m² = 2700 N
Weight is officialy defined as a force
measured in Newtons, but when we
talk about weight we often give it in
Kilograms (a unit of mass).
To get the weight in units of
Kilogram-force you must divide by the
gravitational acceleration =9.81 m/s²
2700 / 9.81 = 275.23 Kg
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define physical quantity
Answer:
The quantity which can be measured is called physical quantity.
Answer:
Those quantities which can be measured are called physical quantities.
A piano technician slides a Steinway grand piano across a level floor at Carnegie Hall. The piano has a mass of 490 kg.
(a) Draw a free-body diagram, and calculate the normal force supporting the piano.
(b) If the coefficient of static friction between the floor and the piano is 0.35, calculate the minimum amount of force needed to get the piano to move.
(c) Once the piano is moving, a horizontal force of 1.1 x 10²N is necessary to keep it moving at a constant speed. Determine the coefficient of kinetic friction.
We have that the normal force is given as [tex]F_N=4802N[/tex],while the minimum amount of force needed to get the piano to move to be [tex]F_f=1680.7N[/tex] and
Coefficient of kinetic friction as [tex]\mu_k=0.23[/tex]
A) [tex]F_N=4802N[/tex]
B) [tex]F_f=1680.7N[/tex]
C) [tex]\mu_k=0.23[/tex]
From the question we are told that:
Mass [tex]m=490kg[/tex]
A)
Generally, the equation for normal force is mathematically given by
[tex]F_N=mg[/tex]
[tex]F_N=(490kg*9.81)[/tex]
[tex]F_N=4802N[/tex]
B)
From the question we are told that:
Coefficient of static friction [tex]\mu=0.35[/tex]
Generally, the equation for Frictional Force is mathematically given by
[tex]F_f=\mu mg\\\\F_f=4802*0.35[/tex]
[tex]F_f=1680.7N[/tex]
C)
From the question we are told that:
Horizontal force [tex]F_h =1.1 * 10^2 N[/tex]
Generally, the equation for coefficient of kinetic friction is mathematically given by
[tex]\mu_k=\frac{F_h}{mg}[/tex]
[tex]\mu_k=\frac{1.1 x 10^2}{4802}[/tex]
[tex]\mu_k=0.23[/tex]
Therefore in conclusion
the normal force is given as [tex]F_N=4802N[/tex],while the minimum amount of force needed to get the piano to move to be [tex]F_f=1680.7N[/tex] and
Coefficient of kinetic friction as [tex]\mu_k=0.23[/tex]
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A car moves with an average speed of 45 mph. How long does a car take to travel 90 miles?
Answer:
It took 2 hours
Explanation:
[tex]{ \bf{time = \frac{distance}{speed} }} \\ [/tex]
distance is 90 miles
speed is 45 miles per hour
[tex]t = \frac{90}{45} \\ \\ t = 2 \: h[/tex]
Answer:
2 hours
Explanation:
45 times 2 is 90
A car is moving with a speed of '20" "m//s' , after applying the break it has come to rest after 10 seconds. What is its acceleration?
4:36 PM
How high can a human throw a ball if he can throw it with initial velocity 90 kph
Answer:
90 km/hr= 90000/3600=25 m/s initial velocity
-25/ 2 (-4.9)= 2.551 secs
h(2.551)= -4.9 (2.551)² + 25(2.551)=-31.8872449+63.775 = 31.8m
The distance would be 31.8 meters, also that person will have sore arm.
Help with the question I know this question is simple but i am weak in physics
Answer:
F = G M1 M2 / R^2
R^2 = G M1 M2 / F
R^2 = 6.67 E-11 * 6.78 E26 * 5.42 E20 / 8.6 E10
R^2 = 6.67 * 6.78 * 5.42 / 8.6 * E25
R^2 = 28.5 * E25 = 2.85 * E26
R = 1.69 E13 m
plzz can anyone solve this
plzzzz guys tomorrow is my exam ..
plzz
Answer:
i hope it helped U
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Burger Hut is trying to decide if it can receive money from the government for providing employees with insurance. Financial accounting or Management Accounting or Tax Accounting
We have that with these disciplines well defined, The Form of accounting that speaks the most Burger Huts situation is the discipline of Management Accounting
Firstly we define the Disciplines of Accounting below
Financial accounting
Financial Accounting, this is a branch of accounting that focuses mainly on the Recording,Encapsulating or Summing up and then Releasing a statement bearing the Affairs of a Business over a specific time frame.
Management Accounting
This Branch of accounting focuses on the use of existing Financial positions to make assessment of a business and determine the best way to move the business forward.
Tax Accounting
This is a branch of accounting that focuses on taxation.This branch is governed by stiff rule that ensure that business stay in check.
Therefore
With these disciplines well defined, The Form of accounting that speaks the most Burger Huts situation is the discipline of Management Accounting
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Is ambition a good or bad thing?
Answer:
some amount of ambition is good for your motivation but excess ambition is dangerous.
the forces which hold molecules in a water drop are called choose surface tension adhesive or cohesive forces yessfgb
Answer:
Cohesion
Explanation:
Cohesion is the force responsible for holding the molecules of water together.
Adhesion is type of force between two different molecules or compounds.
Surface tension allows water molecules or molecules to resist any external force "due" to cohesive forces.
[tex]\rule[225]{225}{2}[/tex]
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~AH1807Peace!write si units of the following physical quantities volume , potential difference, temperature, electrical resistance
Answer:
cubic meter - Volume
Volt - potential difference
kelvin - temperature
ohm - electric resistance
Explanation:
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help me please i dont understand
Answer:
inertia is due to friction
13 The pressure of the atmosphere is 100 000 Pa
a Calculate the force with which the atmosphere presses on the outside of a large window 2.0m
high and 1.25m wide.
bExplain why this force does not break the window.
Question:-
(A) The pressure of the atmosphere is 100000 Pa Calculate the force with which the atmosphere presses on the outside of a large window 2.0m high and 1.25m wide.
(B) Explain why this force does not break the window.
Answer:-(A)
As we know
[tex]Formula -> pressure = {force} \times area[/tex]
Given->
Pressure-> 1atm
height-> 2 m
wide -> 1.25 m
Putting value in formula ->
[tex]100000 = force \times(h \times w) \\ 100000= force \times 2 \times 1.25 \\ force = \frac{100000}{2 \times 1.25}\\ force = {4×10000}\\ force = 40000\: newton \: (N)[/tex]
(B) Because atmosphere is present on both sides of the window pane so same force is applied from both sides of the window and as we know force is a vector quantity so according to the vector sum the force got cancelled out and net force becomes zero .
That's why even in presence of this amount of force window glass donot break
a) The force with which the atmosphere presses on the outside of the window be 3 × 10⁵ Newton.
b) As the atmosphere exerts thus much force on either side of the window, the opposing forces cancel one another out. The window is not broken by this force, therefore.
What is pressure?It is the ratio between the force being applied and the surface area being applied to. Pressure can be described as: the force applied perpendicularly to an object's surface divided by the surface area over which it is applied.
Given parameters:
The pressure of the atmosphere is 100000 Pa
Height of the large window: h = 2.0 m.
Width of the large window: d = 1.5 m.
surface area of the window = h×d = 2×1.5 m² = 3.0 m².
Hence, the force with which the atmosphere presses on the outside of the window = pressure × surface area
= 100000 Pa × 3.0 m².
= 3 × 10⁵ Newton.
b) As the atmosphere applies this amount of force in both side of the window, each two each an opposite force nullifies each other. So, this force does not break the window.
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After 14.1s, a jogger's displacement is 520m. What is the average velocity in km/h
The average velocity in km/hr is 132.99km/hr
The first step is to convert 14.1 secs to hours
14.1/3600
= 0.00391 secs
Convert 520 m to km
520/1000
= 0.52 km
Velocity= displacement/time
0.52/0.00391
= 132.99km/hr
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Which of the following exhibits different types of motion
a=motion of the earth
b=car moving on the road
c=motion of sewing machine
True or false? Balanced forces cause a change in motion. T/F
How do you know this?
Help me, it's due soon!
Balanced forces do not change the motion of an object, Because the forces are the same size and acting in opposite directions.
Answer:
Balanced forces do not change the motion of an object. The motion of an object will not change if the forces pushing or pulling the object are balanced. An object that is sitting still will stay still if the forces acting on it are balanced.
When moving across a period from left to right in the periodic table, excluding transition elements, which trend occurs?(1 point)
Valence electrons increase by one.
Valence electrons decrease by one.
The energy levels increase by one.
The energy levels decrease by one.
Answer:
Valence electrons increase by one
The 'Periodic Table' is characterized as the 'tabular representation of chemical elements as per their atomic number in order to keep the elements possessing similar properties in a single group.'
In case one moves towards right from left in this table except for the transition elements, the trend that occurs would be:
A). Valence electrons increase by one.
'Valence electrons' are described as 'any of the electrons that are present in an atom's outermost shell.' These are the electrons that possess the ability to develop bonds with other present atoms. The valence electrons present increase by one unit to maximum of 4 units in the period if we move from the left towards the right leading to an enhanced charge on the nucleus.Thus, option A is the correct answer.
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hi pls answer 11 point pls
Answer:
the answer is a. a ball is moving towards the camera faster then slower
A cat runs 80 meters to the left in 16 seconds, then 50 meters to the right in 10 seconds, then 70 meters to the left in 14 seconds, then 40 m to the right in 8 seconds.
a. What was the distance travelled by the cat?
b. What was the displacement of the cat?
c. What was the average speed of the cat?
d. What was the average velocity of the cat?
Explanation:
a) Distance ➤ (80+50+70+40) m. ➤ Distance= 240m.
b) Displacement ➤ (50+40)m. ➤ Displacement= 90m
c) Average Speed ➤ Total distance travelled/total time taken
➤ 240/48
➤ 5 [tex]ms^{-1}[/tex]
d) Average Velocity ➤ Total displacement/total time taken
➤ 90/48
➤ 1.875 [tex]ms^{-1}[/tex]
Which characteristic accounts for the fact that red lights in dark rooms and DO NOT expose negatives during developing?
Answer:
the long wavelength and not focused on the negatives.
A cyclist travels at 15 m/s during a sprint finish. What is this speed in km/h
Answer:
54km/hr
Explanation:
Since we have to complete m/s to km/h.
we can simply divide the m/s by (5/18)
so we get 54km/hr
Which types of changes must follow the law of conservation of mass?
Both physical and chemical changes
Neither physical nor chemical changes
Only physical changes
Only chemical changes
Answer:
Both physical and chemical changes
Answer:
Both physical and chemical changes follow the law since when the system is closed to all transfers of matter and energy, the mass of the system must remain constant over time, irrespective of the state.
Explanation:
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3. Write any two differences between contact force and not contact force with examples.
Explanation:
Contact force includes applied force, the normal force, the tension and the frictional force. Non-contact force includes electro-magnetic force, the gravitational force and the electrostatic force. For Example, applied force is required to kick the ball else the ball would not move.
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34.1 grams / 1.1 mL =
General formula,
→ 1 mL = 1 gram
The given question is,
→ 34.1 grams / 1.1 mL = ?
According to the formula,
→ 34.1 grams / 1.1 grams
→ 34.1 ÷ 1.1
→ 31 grams
The answer is 31 grams.
who is the most genius scientist in the world
Answer:
Marie Curie
Explanation:
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How many marbles would fit in beta Centauri?
Answer:
dude if any body could answer that they deserve a Nobel prize because the formula to solve that would require the exact measurement of hadar or as commonly known beta centauri
Explanation:
10th grade Physical Science.... Help plss
1.) Which option is a negatively charged ion?
A) chloride
b) chlorate
c) chlorite
d) chlorine
2.) When moving across a period from left to right in the periodic table, excluding transition elements, which trend occurs?
a)Valence electrons increase by one.
b)The energy levels increase by one.
c)Valence electrons decrease by one.
d)The energy levels decrease by one.
3.) Which information about an atom can a period number give you?
a)the number of valence electrons it has
b)the ionic charge it forms
c)how many bonds it will make
d)how many energy levels it has
4.) Fluorine has 7 valence electrons. Which charge is its ion likely to have?
a)5+
b)1–
c)5-
d)1+
5.)Which two elements in the list would bond together based on their ionic charges?
a)calcium and potassium
b)potassium and iodine
c)calcium and neon
d)potassium and neon
Use the list to answer the question.
potassium, Group 1
calcium, Group 2
iodine, Group 17
neon, Group 18
The periodic table is an arrangement of elements into groups and periods based on their periodic properties. Elements a placed in these groups and periods.
1) A negatively charged ion is chloride
2) Moving from left to right, valence electrons increase by one.
3) The period number gives information about how many energy levels it has
4) Fluorine has a charge of 1–
5) Potassium and iodine form an ionic bond.
In the periodic table, elements are arranged in groups and periods. There are 18 groups and 8 periods.
Chlorine is in group 17, there have seven outermost electrons hence the chlorine atom needs only one more electron in order to attain a stable octet. This is done by accepting one electron to form the negatively charged chloride ion.
As we move from one period to another, one extra electron is added to the outermost shell of elements. Hence, the valence electrons increases by one.
The period to which an element belongs shows you the number of shells or energy levels in the atom of that element.
Fluorine is in group 17. One electron is needed to achieve a stable octet. When an atom accepts one electron, its charge is 1–.
Bonding based on ionic charges occurs between metals and nonmetals. Potassium is a metal of group 1 and iodine is a non metal of group 17 hence they can bond together based on their ionic charges.
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Nikki has a momentum of 45 Kilogram meters per second and a mass of 30 Kilograms. What is her velocity?
Answer:
45/30
Explanation:
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Nikki has a momentum of 45 Kilogram meters per second and a mass of 30 Kilograms. then her velocity would be 1.5 meters per second
What is momentum?It can be defined as the product of the mass and the speed of the particle, it represents the combined effect of mass and the speed of any particle, and the momentum of any particle is expressed in Kg m/s unit.
Mathematically the formula of the momentum is
P = mv
where P is the momentum of the particle
m is the mass of the particle
v is the velocity by which the particle is moving
As given in the problem Nikki has a momentum of 45 Kilogram meters per second and a mass of 30 Kilograms
P = 45 Kilogram meters per second
m = 30 Kilograms
By substituting the values of the momentum and the mass in the formula of the momentum
P = mv
45 = 30 ×v
v = 45/30 meters per seconds
v = 1.5 meters per seconds
Thus, Nikki weighs 30 kilograms and moves at a 45 kilogram per the second momentum. subsequently, her velocity would be 1.5 meters per second.
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