They realized this as result of the number of sunspots getting larger and smaller over the course of the years .
What is Sunspot?This is defined as a temporary phenomena on the Sun's photosphere that appear as spots darker than the surrounding areas.
The presence of these sunspots is what gave Astronomers the idea of the Sun having varying levels of activities over the years.
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what are ohmic resistors?
An ohmic resistor is a resistor that obeys Ohm's law V = IR (voltage = current x resistance). Therefore, if the voltage in such element is increased by n number of times, by the same number n has to increase the current.
[tex] \\ [/tex]
hope it helps:)
Ohmic resistors are materials that obeys ohms law.
What is ohmic resistor?An ohmic resistor is a material that obey's ohms law. This material does not allow passage of electricity through it.
V = IR
where;
I is the current in the conductorR is the resistanceV is the voltageThus, ohmic resistors are materials that obeys ohms law.
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A building under construction requires building materials to be raised to theupper floors by cranes or elevators. An amount of cement is lifted 76.2 m by acrane, which exerts a force on the cement that is slightly larger than the weightof the cement. If the network done on the cement is 1.31 × 103 J, what is themagnitude of the net force exerted on the cement?
Answer:
17.19NExplanation:
Work = 1.31 × 10³ = 1310
F = W/D = 1310/76.2
≈ 17.19N
An amount of cement is lifted 76.2 m by arcane, which exerts a force on the cement that is slightly larger than the weight of the cement. If the network done on the cement is 1.31 × 103 J, 17.19N is the magnitude of the net force exerted on the cement.
What is force?In mechanics, force is defined as any action that seeks to sustain or modify the movement of a body or even to deform it. The idea of force is frequently defined in terms of Isaac Newton's three laws of motion, which are laid forward by book Principia Mathematica (1687).
Newton's first principle is that a body at rest and moving uniformly inside a single direction will continue in that condition unless another force is exerted to it.
Work = 1.31 × 10³ = 1310J
Force = Work/Distance
= 1310/76.2
≈ 17.19N
Therefore, 17.19N is the magnitude of the net force exerted on the cement.
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Help ASAPP!!!!!
Which of these is measured during a scientific investigation?
Test variable (independent variable)
Outcome variable (dependent variable)
Control group
Hypothesis
Answer:
A hypothesis predicts the value of a dependent variable given an independent variable:
If a person weighs 50 kg (independent variable) the weight hypothesis predicts that W = 50 * 9.8 = 490 N (the dependent variable)
So those three should be present in an investigation
How much impulse is required to change the velocity of a 2500 kg truck by 15 m/s?
Answer:
A car weighing 2500 kg and travelling at 15 m/s stops at a distance of 25 m deceleration uniformly. What is the force exerted on it by the brakes?
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5 Answers
Naren Nagarajan
, Cambridge Examinations Officer at Kasiga School, Dehradun (2008-present)
Answered 3 years ago · Author has 1.1K answers and 1.9M answer views
(a) W= Fd ( energy = force x distance )
(b) KE = .5 m v*v ( Kinetic energy of the car )
KE =0.5 * 2500 * 225KE =281250 Joules
Using (a) , Reducing kinetic energy to zero over 25 m
281250 = F * 25
F = 281250 /25
F = 11250 N
To check or use a different method …..
v^2 = u^2 +2as ( Third equation of motion )
2as = v^2 -u^2 ( v = 0 and U = 15 )
as = -225/2
a = - 225/2 * 25
a= - 225/50
a= - 4.5 m sec ^ -2
F = ma
F = 2500 * - 4.5
F = - 11250 N ( the negative sign indicates that the force is opposite in direction to the motion of the car )
The answer is correct since both values for F are equal.
a bomb sitting at rest on a table explodes into four pieces of equal mass. the first piece travels to the south at a velocity of 55.0 m/s. the second piece travels to the west at a velocity of 80.0 m/s. the third piece travels at a velocity of 40.0 m/s [30.0 w of n]. what is the velocity of the fourth piece?
The velocity of the fourth piece after the explosion is 118.5 m/s at 14.7⁰ east of north.
Conservation of linear momentumThe principle of conservation of linear momentum states that the sum of the initial momentum is equal to sum of final momentum.
Initial momentum of the bomb before explosion is equal to the final momentum of pieces of bomb after explosion.
Pi = Pf
0 = P₁ + P₂ + P₃ + P₄
0 = mv₁ + mv₂ + mv₃ + mv₄
0 = v₁ + v₂ + v₃ + v₄
Resolve the velocity into x and y componentsConsider x-y plane for the velocity of the piece of bomb;
Let southward = negative directionLet northward = positive directionLet eastward = positive directionLet westward = negative direction[tex]0 = (v_1x + v_1y) + (v_2x + v_2_y) + (v_3x + v_3_y) + (v_4_x + v_4_y)\\\\0 = (0 - 50y) + (-80x + 0) + (-40cos30x + 40sin30y) + (v_4_x + v_4_y)\\\\0 = -50y -80x - 34.64x + 20y + v_4_x + v_4_y\\\\0 = -30y - 114.64x + v_4_x + v_4_y \\\\v_4_x + v_4_y = 114.64x + 30y\\\\|v_4| = \sqrt{114.64^2 + 30^2} \\\\|v_4| = 118.5 \ m/s\\\\tan(\theta ) = \frac{30}{114.64} \\\\tan(\theta) = 0.262\\\\\theta = tan^{-1} (0.262)\\\\\theta= 14.7 \ ^0[/tex]
Thus, the velocity of the fourth piece is 118.5 m/s at 14.7⁰ east of north.
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What is the electric current measured in
An ampere (AM-pir), or amp
Ben lifts his 12kg daughter in the air from the ground to a height of 2.2m. How much work has he done? (Remember that weight = mass x gravitational field strength. Assume that g=10N/kg)
W= mg × d × cosx
W= 12 × 10 × 2.2 × (-1)= -264 J
I hope it helps you
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The fork-lift truck lifts a crate of mass 64 kg through a vertical distance of 3.5 m in 4.0 s.
Calculate the useful work done in lifting the crate.
The amount of work done by the fork-lift truck in lifting the crate is 2,195.2 Joules.
Given the following data:
Mass of crate = 64 kg.Displacement = 3.5 meters.Time = 4.0 s.Scientific data:
Acceleration due to gravity = 9.8 [tex]m/s^2[/tex].To calculate the amount of work done by the fork-lift truck in lifting the crate:
How to calculate work done.In Science, work done is generally calculated by multiplying force and the vertical distance or displacement experienced by an object.
Mathematically, work done is given by the formula:
[tex]Work\;done = force \times displacement = mgh[/tex]
Substituting the given parameters into the formula, we have;
[tex]Work\;done = 64 \times 9.8 \times 3.5[/tex]
Work done = 2,195.2 Joules.
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The source of a sound moves away from the listener. The listener has the impression that the source is __________.
Explanation:
As the source of sound waves approaches you the sound waves get closer together, increasing their frequency and the pitch of the sound. The opposite happens when the source of sound waves moves away from you
How is it possible to lift a heavy car with a small force?
Answer:
By applying relative small force to the smaller piston
Explanation:
If a car sits on top of the large piston, it can be lifted by applying a relatively small force to the smaller piston, the ratio of the forces being equal to the ratio of the areas of the pistons
What iz inertia ? -,-
Inertia refers to the tendency of a body to resist changes.
InertiaIt is the property of a body to resist change.
A moving body will continue moving until a force acts on it. Unless the acting force is big enough to overcome the inertia of the body, the body will continue moving.
Also, a body at rest will continue resting unless a force big enough to overcome the inertia force is used to displace it.
More on inertia can be found here: https://brainly.com/question/1358512
Answer:
inertia, property of a body by virtue of which it opposes any agency that attempts to put it in motion or, if it is moving, to change the magnitude or direction of its velocity. Inertia is a passive property and does not enable a body to do anything except oppose such active agents as forces and torques.
The mass after a physical change, such as ice melting into water, stays the same a. -true b. -false.
Answer:
Yes, it can be destroyed.The total amount of matter (atoms) before and after a chemical reaction (change), remains the same.
Explanation:
hope this helps
What intermolecular force is the closest representation to the interaction between the balloon and the water?
The intermolecular force is the closest representation to the interaction between the balloon and the water is Dipole-Dipole interaction.
What is intermolecular force?
The intermolecular force is the force of attraction between atoms, molecules, and ions when they are placed close to each other.
This force denotes the miscibility of polar solvents and their interacting characteristics like melting points and boiling points.
Thus, the intermolecular force is the closest representation to the interaction between the balloon and the water is Dipole-Dipole interaction.
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if a 15 kg box is lifted up 3 meters, how much work is done?
Answer:
I believe the answer is 45
A 39-Ω resistor is connected across a 45-V battery. A. What is the current in the circuit? b. How much energy is used by the resistor in 5. 0 min?
Answer with explanation
a) Formula to find the current that passes through a circuit is :
Voltage = Current × ResistanceGiven that,
Voltage = 45V
Resistance = 39Ω
Current =?
Let us find it now.
V = I × R
45V = I × 39Ω
Divide both sides by 39.
1.153A = I = Current
b) Formula to find the energy is:
Energy = voltage × current × time= 45V × 1.153A × ( 5 × 60)s
= 15565.5 J
= 15.5655kJ
The bonds of the products store 22kJ more energy than the bonds of the reactants. How is energy conserved during this reaction?
A. The reaction uses up 22kJ of energy when bonds break.
B. The reaction creates 22kJ of energy when bonds form.
C. The reaction system absorbs 22kJ of energy from the surroundings.
D. The surroundings absorb 22kJ of energy from the reaction system.
whoever gives a detailed explanation will get branliest
Help!!
I need correct answer:)
Answer:
4 independent of l and area of cross section
Option D
It's independent of.lemgth or area of cross section of the wire.As
Breaking stree depends upon the material of the wire .steel bars, each of length 3cm at 29°c are to be used for constructing a rail line. lf the linear expansivity of steel is 1.0×10^-5k^-1, calculate the safety gap between successive bars if the highest temperature expected is 41°c
Answer:
Hi, Im Jenna! Here is ur ansswer Pls mark as braijnliest
Explanation:
solution.
The formula for linear expansivity is
α = (If – If) / If (0f – 0i ) is used to determine the linear expansivity
If – final length,
I – initial length
0f – final tempt.
0i – initial tempt.
(b) (ii)
I = 3 m
0 = 29oC
02 = 41oC
α = 1.0 x 10 k-1
using safety gap = change in length
Δ l = α I Δ Θ
1 x I0-5 x 3.0 x (41 – 29) = 3.6 x 10-3 m = 0.0036
When you stand on the merry-go-round in question 12, you hold a string from which
is suspended a rubber stopper of mass 45 g. You are 2.9 m from the centre of the
merry-go-round. You take 4.1 s to complete one revolution. What angle does the string make with the vertical?
The angle the string makes with the vertical is : 34.6°
Given data :
mass of rubber stopper ( m ) = 45 g
Radius ( r ) = 2.9 m
Time to complete one revolution ( T ) = 4.1 secs
Calculate the angle the string makes with the verticalapplying the formula below
Tan ∅ = [tex]\frac{mw^2r}{mg}[/tex] --- ( 1 )
cancel out m from equation ( 1 )
Tan ∅ = [tex]\frac{w^2r}{g}[/tex] ----- ( 2 )
where ; w = [tex]\frac{2\pi }{T}[/tex]
Therefore equation ( 2 ) becomes
Tan ∅ = [tex]\frac{4\pi ^2r}{T^2g}[/tex] --- ( 3 )
where ; r = 2.9 m, T = 4.1 secs , g = 9.8
Insert values into equation ( 3 )
Tan ∅ = 0.69
∅ = Tan ( 0.69 )
= 34.6°
Hence we can conclude that The angle the string makes with the vertical is : 34.6°.
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if an object moves from a position of x = 12 m to x = 124 m, then back to x = 98 m. If the time it takes to complete this motion is 10 s, what is the average velocity of the object?
Answer:
13.8m/s
Explanation:
Speed = Distance/Time
Since the object moved 138m over 10s we just substitute it in.
Speed = 138/10s
Speed = 13.8m/s on Average
Anyone knows the answer to this?
It shows the graph of a car's acceleration and its asking what's the acceleration around 6 seconds and 7 seconds.
Answer:
B 7.5mph/s
Explanation:
use change in y/ change in x
Easy point...
Why the gravity is zero at the centre of earth?
Note:-
✯ No spam
✯ No copied answers
✯ No short answers
Let's see why g is 0 at centre of earth
[tex]\\ \rm\rightarrowtail g\propto \dfrac{1}{h}[/tex]
Means g is indirectly proportional to height of object.
If height is more gravity is lessIf height is less gravity is moreAt centre h=0
So if height is 0 then gravity is also zero.And at centre the distance from top of earth surface is equal in opposite directions from centre.
So
[tex]\\ \rm\rightarrowtail F_{net}=0[/tex]
So gravity remains 0Hello! Answer is below.
The center of the earth has no gravity, at all, since its pulling on you in all other directions (hints to why you can float if you were in a room/ spaceship, since there are so many massive objects).Gravity pulls us because there are massive objects that exert a gravitational force on everything around them. The further away the object is, the weaker the force is. For exapmple, if all those massive objects dissapeared, we would be able to walk freely. Meaning,we could walk the way we do on earth.
Hope this helps.
-Natalia.
My aunt and uncle live somewhere in south Florida near the beach
A 6.0 kg metal ball moving at 4.0 m/s hits a 6.0 kg ball of putty at rest and sticks to it. The two go on at 2.0 m/s.
(a) What is the kinetic energy of the metal ball before it hits?
(b) What is the kinetic energy of the metal ball after it hits?
(c) What is the kinetic energy of the putty ball after being hit?
(d) How much energy does the metal ball lose in the collision?
(e) How much kinetic energy does the putty ball gain in the collision?
(f) What happened to the rest of the energy?
The metal ball lost energy while the putty ball gained energy.
What is momentum?Momentum is the product of mass and velocity of the body. We must note that momentum before collision is equal to momentum after collision.
1) Kinetic energy before collision = 1/2mv^2 = 0.5 * 6 * 4 = 12 J
2) kinetic energy after collision = 0.5 * 6 * 2= 6 J
3) Kinetic energy of putty ball = 0.5 * 6 * 2= 6 J
4) Energy lost by the metal ball = 12 J - 6 J = 6 J
5) Energy gained by the putty ball = 6 J - 0J = 6 J
6) The rest of the energy was converted to heat after the collision.
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help me please (｡'-‿-｡)
Answer:
the layers of atmosphere are heated through radiation and convection.
Explanation:
heat is transferred from sun through radiation
and current through convection
What is the difference between a reflected and a diffracted sound wave?.
Answer:
a reflected sound wave completely bounces off an object and diffraction occurs when there is an opening in a wall and only the waves that can fit through the wall go and then the waves start to expand again after going through the hole.
Explanation:
what is the best matral or mechaniazime to use in a egg drop form 30 feet
Answer:
Ok so there are many ways to go at this.
you can get a zip lock bag and put a bunch of plastic around the egg inside the bag. (image down below)
Just anything to slow down the descent speed.
Cushion the egg so that something other than the egg itself absorbs the impact of landing.
Explanation:
Before your interview ends, make sure to ask these questions:Will you please call me with the hiring decision?Will you please call me with the hiring decision?Is there a target date for the hiring decision?Is there a target date for the hiring decision?Are you interviewing any other applicants?Are you interviewing any other applicants?What is your preferred method for follow-up contact?What is your preferred method for follow-up contact?
Answer:
A and B
Explanation:
got it right
Answer:
Is there a target date for the hiring decision?
What is your preferred method for follow-up contact?
What is the half-life radioactive isotope?
Answer:
The half-life of a radioactive isotope is the time taken for half the unstable nuclei in a sample to decay.
A dog pulls on its lead (spring constant 10N/m), the lead extends by 0.1m. How much force did the dog apply to the rope?
Answer:
1N
Explanation:
F=ke
k=10N/m
e=0.1m
F=10*0.1
F=1N
