can someone help me? i will give brainliest

Answer:

B. [tex]F = -k*x[/tex]

Explanation:

The force of a spring can be easily calculated using Hooke's law which tells us that the force applied on a spring is equal to the product of the constant of a spring by the compressed or stretched distance of the spring.

That is:

[tex]F = k*x[/tex]

k = spring constant [N/m]

x = distance [m]

Answer:

A

Explanation:

Hopefully this helps

Two ice skaters are at rest and facing each other. In order to move, they push off each other, then their net final total momentum must equal zero, therefore the correct answer is option C.

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.

As given in the problem statement two ice skaters are at rest and facing each other. In order to move, they push off each other,  

By using the conservation of the momentum,

The initial total momentum of two skaters = the final total momentum of the skaters

Since, initially, they are at rest and their initial total momentum is zero  therefore the correct answer is option B

To learn more about momentum from here, refer to the link;

brainly.com/question/17662202

#SPJ5

Answer:

it has the same mechanicals as a baseball

Explanation:

Answer:

a change in velocity can be a change in magnitude (or speed), but it can also be a change in direction.

Answer: 121.2 m/s

Explanation:

Here we will use the conservation of energy.

We can write the total energy of an object as:

E = K + U

For this particular case we have:

K = kinetic energy = (m/2)*v^2

U = potential energy = m*g*h

where:

m = mass of the object.

g = gravitational acceleration = 9.8m/s^2

h = height at which the object is dropped, in this case 750m

v = velocity of the object.

Right when the packet is dropped, it's velocity is equal to zero, this means that there is no kinetic energy and only potential energy, then we have:

Ei = Ui = m*9.8m/s^2*750m = m*(7350m^2/s^2)

And when the object is about to hit the ground, h will be almost equal to zero, this will mean that we will have only kinetic energy, and because of the conservation of energy, this final energy must be the same as the initial energy, then we will have

Ei = Ef

m*(7350m^2/s^2) = Ef = Kf

m*(7350m^2/s^2) = (m/2)*v^2

We can divide by m in both sides to get:

(7350m^2/s^2) = (1/2)*v^2

√( 2*(7350m^2/s^2)) = v = 121.2 m/s

Then the velocity of the packet when it reaches the ground is 121.2 m/s

The complete question is

A 45-kg child sits on a 3.2-kg tire swing. The tension on the rope is 470 N. The tree branch sags and the child's feet rest on the ground. If the tension in the rope is reduced to 220 N, what is the value of the normal force being exerted on the child's feet?

Answer:

Therefore the Normal force is being exerted on the child's feet is 252.36( 250N).

Explanation:

We are given

mass of child = 45kg

mass of the tire = 3.2kg

g = 9.8 m/s^2

We have the first case in which the tire is in swing so tension in that case will be which is the resultant force.

Fr = Resultant force

Ft =  Tension force

Fg= Gravitational force

Fr = Fg + Ft

0 = -mg + Ft

Ft = mg

   = (45+3.2)*9.8

   = 48.2 * 9.8

Ft = 472.36N  ( which is close to 470)

In the second case the child is in the rest position, The resultant force will be zero.

Fr = Ft + Fn + Fg  ( Normal force is denoted by Fn )

0 = Ft + Fn + Fg

Fn =  -Fg -Ft

Fn = mg -Ft

    = 472.36 - 220

Fn  = 252.36N  ( close to 250N)

Therefore the Normal force being exerted on the child's feet will be 252.36N.  

Answer:

[tex]1\ \text{W/m}^2[/tex]

[tex]0.0039\ \text{W/m}^2[/tex]

Explanation:

[tex]I_1[/tex] = Intensity of sound at 2 m away

Sound level = 120 dB

[tex]r_1[/tex] = 2 m

[tex]r_2[/tex] = 32 m

[tex]I_0[/tex] = Threshold of sound = [tex]10^{-12}\ \text{W/m}^2[/tex]

Sound level is given by

[tex]dB=10\log (\dfrac{I_1}{I_0})\\\Rightarrow I_1=10^{\dfrac{dB}{10}}I_0\\\Rightarrow I_1=10^{\dfrac{120}{10}}\times 10^{-12}\\\Rightarrow I_1=1\ \text{W/m}^2[/tex]

The intensity of sound at 2 m away is [tex]1\ \text{W/m}^2[/tex]

[tex]I_1=\dfrac{P}{4\pi r^2}[/tex]

[tex]I\propto \dfrac{1}{r^2}[/tex]

[tex]\dfrac{I_1}{I_2}=\dfrac{r_2^2}{r_1^2}\\\Rightarrow I_2=\dfrac{I_1r_1^2}{r_2^2}\\\Rightarrow I_2=\dfrac{1\times 2^2}{32^2}\\\Rightarrow I_2=0.0039\ \text{W/m}^2[/tex]

The intensity of the sound 32 m away is [tex]0.0039\ \text{W/m}^2[/tex]

One chemical property of the bleach is its pH.

This is referred to as the power of hydrogen and is a measure of how acidic/basic a substance is.

pH is an example of  chemical property because it's associated with a change in its chemical composition. This thereby makes option D the most appropriate choice.

Read more about pH here https://brainly.com/question/4137247

Answer:   It's   pH

Explanation:   I took the test

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Your answer is 0.30 seconds

Acceleration due to gravity depends directly on the mass of Earth and inversely to the square of radius of Earth.

Answer:

9.8 m/s2

Explanation:

Acceleration due to gravity is the acceleration gained by an object due to the gravitational force. Its SI unit is m/s 2. It has both magnitude and direction, hence, it’s a vector quantity. Acceleration due to gravity is represented by g. The standard value of g on the surface of the earth at sea level is 9.8 m/s2.

Answer:

B). Rarefaction :) _____

the arrow points to the rarefactions

Answer:

false

Explanation:

Answer:

there are 64 cups

Explanation:

remember this: two cups in a pint, two pints in a quart, two pints in a quart, four quarts in a gallonl2

Answer:

Winter

Explanation:

Answer:

150 N

Explanation:

Force is equal to mass times acceleration.  50 kg accelerating at a mass of 3m/3² is undergoing a force of 150 m/s², or 150 Newtons

Answer:

a. 3.68 m b. 0.61 m c. 3.07 m

Explanation:

a. What is the maximum height the ball reaches on the moon?

Using v² = u² - 2g'h where u = initial velocity of baseball = 12 m/s, v =  final velocity of baseball = 0 m/s (since it stops at maximum height), g' = acceleration due to gravity on moon = g/6 where g = acceleration due to gravity on earth = 9.8 m/s², so g' = 9.8 m/s²/6 = 1.63 m/s² and h = maximum height of ball on moon.

So, making h subject of the formula, we have

h = -(v² - u²)/2g'

substituting the values of the variables, we have

h = -((0 m/s)² - (12 m/s)²)/2(1.63 m/s²)

=  -(- 12 m²/s²)/2(1.63 m/s²)

= 6 m²/s²)/(1.63 m/s²)

= 3.68 m

b. What is the maximum height the ball reaches on the earth?

Using the same equation for the maximum height the baseball travels on the moon for that on the earth, the maximum height h' the baseball travels on the earth is given by  

h' = -(v² - u²)/2g where u = initial velocity of baseball = 12 m/s, v =  final velocity of baseball = 0 m/s (since it stops at maximum height),  g = acceleration due to gravity on earth = 9.8 m/s²and h' = maximum height of ball on moon.

substituting the values of the variables, we have

h = -((0 m/s)² - (12 m/s)²)/2(9.8 m/s²)

=  -(- 12 m²/s²)/2(9.8 m/s²)

= 6 m²/s²)/(9.8 m/s²)

= 0.61 m

c. What is the difference in the maximum height the ball reaches on the Moon compared to on Earth?

The difference in the maximum height the ball reaches on the Moon compared to on Earth is d = h - h' = 3.68 m - 0.61 m = 3.07 m

Answer:

D

Explanation:

rusting is actually the corrosion of metals so it can't be a way to prevent itself.

Answer: True

Explanation: Light enters your eye through the lens which then hits the retina which is located in the back of your eye.

Answer:it would make it thicker

Explanation:

Answer:

"The equation shows that the current in a circuit is inversely proportional to the resistance of the circuit. An increase in resistance would result in a decrease in current. And the factor by which the resistance increases is the same factor by which the current decreases."

Explanation:

Because it's just like wearing a glove/mitten when getting something out of the oven, because of the insulation from the glove/mitten, it reduces the heat that gets through into your hand, and it protects it. Just like what the "answer" says, it said that the resistance would decrease current.

Answer:

Correct choice: b 4H

Explanation:

Conservation of the mechanical energy

The mechanical energy is the sum of the gravitational potential energy GPE (U) and the kinetic energy KE (K):

E = U + K

The GPE is calculated as:

U = mgh

And the kinetic energy is:

[tex]\displaystyle K=\frac{1}{2}mv^2[/tex]

Where:

m = mass of the object

g = gravitational acceleration

h = height of the object

v = speed at which the object moves

When the snowball is dropped from a height H, it has zero speed and therefore zero kinetic energy, thus the mechanical energy is:

[tex]U_1 = mgH[/tex]

When the snowball reaches the ground, the height is zero and the GPE is also zero, thus the mechanical energy is:

[tex]\displaystyle U_2=\frac{1}{2}mv^2[/tex]

Since the energy is conserved, U1=U2

[tex]\displaystyle mgH=\frac{1}{2}mv^2 \qquad\qquad [1][/tex]

For the speed to be double, we need to drop the snowball from a height H', and:

[tex]\displaystyle mgH'=\frac{1}{2}m(2v)^2[/tex]

Operating:

[tex]\displaystyle mgH'=4\frac{1}{2}m(v)^2 \qquad\qquad [2][/tex]

Dividing [2] by [1]

[tex]\displaystyle \frac{mgH'}{mgH}=\frac{4\frac{1}{2}m(v)^2}{\frac{1}{2}m(v)^2}[/tex]

Simplifying:

[tex]\displaystyle \frac{H'}{H}=4[/tex]

Thus:

H' = 4H

Correct choice: b 4H

Answer:

idgaf

Explanation:

lol

Answer:

Explanation:

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According to Vocal Media,

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Deforestation is the permanent destruction of forests in order to utilize the land or trees. Typically, deforestation is clearing a lot of trees without the intention of establishing future growth. Harvesting, forest fires, and insect infestations do not count as deforestation because the affected areas will eventually grow back.

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Hope this helps! <3

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A) atoms

C) elements

D) molecules

Answer:

radio

Explanation:

Answer:

radio

Explanation:

all except radio use electric motors

Answer:

I believe the answer is B

Answer:

According to the law of conservation of energy, energy cannot be created or destroyed,  although it can be changed from one form to another.    KE + PE = constant. A simple example involves a stationary car at the top of a hill.  As the car coasts down the hill, it moves faster and so it’s kinetic energy increases and it’s potential energy decreases.  On the way back up the hill, the car converts kinetic energy to potential energy.  In the absence of friction, the car should end up at the same height as it started.

This law had to be combined with the law of conservation of mass when it was determined that mass can be inter-converted with energy.

One can also imagine the energy transformation in a pendulum.  When the ball is at the top of its swing, all of the pendulum’s energy is potential energy.   When the ball is at the bottom of its swing, all of the pendulum’s energy is kinetic energy.   The total energy of the ball stays the same but is continuously exchanged between kinetic and potential forms

Answer:

(a) Let the height of the platform is h meter,

=>By s = ut + 1/2gt^2

=>h = 0 + 1/2 x 9.8 x (2.3)^2

=>h = 25.92 m

(b) By R = [Ux] x t

=>R = 2.47 x 2.3

=>R = 5.68 m

Explanation:

Explanation:

From the exercise we know the initial horizontal velocity and the time that Janet takes to land in the water

a) Knowing the formula for free falling objects, we can calculate how high is the platform

At t=2.3m the position of Janet is y=0m

So, the platform is 26m tall

b) According to dynamics the displacement of an object can be analyze using the following formula:

So, Janet lands 6 m far from the base of the platform

Answer:

acceleration due to gravity is always going to be 9.8m/s^2 whenever an object is freely falling.

Explanation:

You could also divide 49.1 m/s by 5s to get an acceleration of 9.8 m/s^2 as well.

Answer:

displacement is the change from a starting point. she ends up back where she started so her displacement is zero meters although she traveled 24m in all.