A child of mass 28 kg swings at the end of an elastic cord. At the bottom of the swing, the child's velocity is horizontal, and the speed is 7 m/s. At this instant the cord is 3.30 m long. (Take the +x direction to be horizontal and to the right, the +y direction upward and +z direction to be out of the page.)

a. At this instant, what is the magnitude of the rate of change of the child's momentum?
b. At this instant, what is the (vector) net force acting on the child?

Answers

Answer 1

Answer:

Explanation:

(A)

Force is said to be the rate of change of momentum.

At the instant, the parallel component of the change of momentum is zero. SInce centripetal force always acts towards the center, hence the direction upwards ( along the positive y-axis).

[tex]\dfrac{dp}{dt} = F(+\hat y)[/tex]

[tex]= \dfrac{mv^2}{r}(+\hat y) \ \\ \\ = \dfrac{28 \ kg \times (7 \ m/s)^2}{3.3 \ m }( + \hat y) \\ \\ = \mathbf{416 \ N ( + \hat y)}[/tex]

(B)

The net force acting on the child is:

[tex]F_{net} = \dfrac{mv^2}{r}( + \hat y) \\ \\[/tex]

[tex]= \dfrac{28 \ kg \times (7 \ m/s)^2}{3.3 \ m }( + \hat y) \\ \\ = \mathbf{416 \ N ( + \hat y)}[/tex]


Related Questions

A snail traveled 3.12 meters in 27.13 minutes. What is the snails speed in meters per second

Answers

Answer:

0.002 m/s

Explanation:

27.13(60) = 1,627.8 seconds

3.12/1,627.8 = 0.00191 ≈ 0.002 = s

Are you sure you're not looking for cm/s?

2. A uniform wire of resistance R is stretched until its length doubles. Assuming its density and resistivity remain constant, what is its new resistance

Answers

Answer:

Resistance is quadrupled.

Explanation:

Solving this requires us to use the formula of resistivity.

Resistivity is usually said to be the measure of the resistance of a particular size of any given material to the electrical conduction. It is mathematically represented as

ρ = RA/L, where

ρ = the resistivity of the given material

R = the resistance of the material

A = the area of the material

L = length of the material.

From the question, we're told that the length is doubled with the resistivity and density remaining constant. If the density is constant, this makes the volume constant as well.

Volume, V = A * L. We're then told that the length is doubled. If the length is doubled, for the volume to remain constant, then the area must be halved.

Volume, V = A/2 * 2L

Making, Resistance R, subject of the formula, we have

R = ρL/A.

Since resistivity is constant and the area is halved, we then have

R = 2L / (1/2A)

R = 4L / A

If the length is doubled, we have the resistance to be quadrupled

Define the term pressure​

Answers

Answer:

Pressure is the perpendicular force applied per unit area.

Pressure could possibly mean force on a certain type of area.....hope this helps!

____ is a chemical messenger released by virus infected cells

Answers

Answer:

Cytokines is the answer

Explanation:

it is another word for the chemical messanger

A small dog is trained to jump straight up a distance of 1.1 m. How much kinetic energy does the 7.7 kg dog need to jump this high?

Answers

Answer:

83.09 J

Explanation:

The potential energy at the point of the top of the jump is represented by the equation

[tex]mgdeltah[/tex]

when the dog jumps, all the potential energy converts to kinetic energy (1/2mv^2). Plugging in the values:

(7.7)(4.184)(1.1) = 83.0907 J

What is the potential energy, if a
body of mass 250 kg is at a height of 30
metre? ​

Answers

PE = (250) (30) (9.81) = 73575J
I used to use 9.81 as acceleration due to gravity. The answer might be different from what you expect

A 10.0-g bullet is fired into, and embeds itself in, a 1.95-kg block attached to a spring with a force constant of 23.9 N/m and whose mass is negligible. How far is the spring compressed if the bullet has a speed of 300 m/s just before it strikes the block and the block slides on a frictionless surface

Answers

Answer: 0.43 m

Explanation:

Given

mass of bullet [tex]m=10\ gm\approx 0.01\ kg[/tex]

mass of block [tex]M=1.95\ kg[/tex]

The Force constant of spring is [tex]k=23.9\ N/m[/tex]

Speed of bullet is [tex]u=300\ m/s[/tex]

Conserving the energy i.e. kinetic energy of the bullet and box is converted into Elastic potential energy of spring

[tex]\Rightarrow \dfrac{1}{2}(M+m)v^2=\dfrac{1}{2}kx^2[/tex]

Conserving linear momentum

[tex]\Rightarrow mu=(M+m)v\\\\\Rightarrow v=\dfrac{mu}{M+m}[/tex]

Put the value of [tex]v[/tex] we get

[tex]\Rightarrow x=mu\sqrt{\dfrac{1}{k(M+m)}}\\\Rightarrow x=0.01\times 300\sqrt{\dfrac{1}{23.9(0.01+1.95)}}\\\Rightarrow x=3\sqrt{\dfrac{1}{46.844}}=\dfrac{3}{6.844}=0.43\ m[/tex]

Thus, spring will be compressed to a distance of [tex]0.43\ m[/tex]

a
The
is a point that lies along a vertical line drawn from the suspension point of an object when the object is at
a standstill.
centripetal force
b. center of mass
c. equilibrium
d. center point

Answers

The answer would be center of mass, B

Can two waves have the
same wavelength but different amplitudes?
Explain

Answers

Answer:

I think Yes because they could have different amounts of energy.

Explanation:

define prism and itz colo​

Answers

Answer:

prism was just a pyramid and if you strike it with white light, the white light then breaks down into 7 colors. (red,orange,yellow,green,blue,indigo,violet)

what dose nuclear reactions produce?

Answers

Answer:

a new chromebook for you and you will get to know the other one that

A 2.35-kg rock is released from rest at a height of 21.4 m. Ignore air resistance and determine (a) the kinetic energy at 21.4 m, (b) the gravitational potential energy at 21.4 m, (c) the total mechanical energy at 21.4 m, (d) the kinetic energy at 0 m, (e) the gravitational potential energy at 0 m, and (f) the total mechanical energy at 0 m.

Answers

Explanation:

Given that,

The mass of rock, m = 2.35-kg

It was released from rest at a height of 21.4 m.

(a) The kinetic energy is given by : [tex]E_k=\dfrac{1}{2}mv^2[/tex]

As the rock was at rest initially, it means, its kinetic energy is equal to 0.

(b) The gravitational potential energy is given by : [tex]E_p=mgh[/tex]

It can be calculated as :

[tex]E_p=2.35\times 9.8\times 21.4\\\\E_p=492.84\ J[/tex]

(c) The mechanical energy is equal to the sum of kinetic and potential energy such that,

M = 0 J + 492.84 J

M = 492.84 J

Hence, this is the required solution.

(a) What do you mean by rest?​

Answers

It’s where the vehicle stops moving.

I hope this helps.

Rhodium is in period 5 of the periodic table. What does this tell you about this element
(It’s number 4 in the picture)

Answers

Rhodium (Rh) is in period 5 on the periodic table. What does this tell you about this element ?

option - D

It has 5 energy levels/shells in its electron cloud.

With the information from the periodic table we can find that the correct statement is:

D. it is 5 energy level

The periodic table of the elements is a method of classifying the chemical elements based on their atomic number, it is divided into rows and columns

The rows are called the period and indicate the energy shell that is filled with electrons, all periods start with one electron and end when the shell is filled with 8 electrons.

The columns called groups correspond to elements that have the same number of electrons in their last shell, the chemical properties of the elements of the group are similar.

In this case we have an element the Rhodium, from period 5 and group VIIIB, when reviewing the period table it can be indicated that it has properties similar to cobalt and the inner layer is filled with two electors in its last layer.

When reviewing the different claims

a) False. The periodic table is not about molecules but about atoms

b) False. The metallic characteristics depend on the relationship between the number of electrons and the fermi level that is not indicated in the periodic table.

c) False. The number of protons is equal to the atomic number, in this case the rhodium has Z = 45, therefore it has 45 protons in the nucleus

d) True. It is at level 5 since the energy levels and the periods coincide.

In conclusion, with the information from the periodic table, we can find that the correct statement is:

D.  it is 5 energy level

learn more about the periodic table here:

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Two tugboats pull a disabled supertanker. Each tug exerts a constant force of 1.80×106 N , one at an angle 14.0 ∘ west of north, and the other at an angle 14.0 ∘ east of north, as they pull the tanker a distance 0.800 km toward the north. Part A What is the total work done by the two tugboats on the supertanker?

Answers

Answer:

W = 1,049 10⁹ J

Explanation:

Work is defined by the relation

         W = F. d = F d cos θ

where tea is the angle between the forces and the displacement.

The total work is the sum of the work of each tug.

Tug 1

       W₁ = F d cos θ₁

 

the angle measured from the positive side of the x-axis is

       θ₁ = 14 + 90 = 104º

           

tugboat 2

             W₂ = F d cos θ₂

             θ₂ = 14

we substitute

             W = F d cos θ₁ + F d cos θ₂

             W = F d (cos θ₁ + cos θ₂)

               

let's calculate

             W = 1.80 10⁶  800 (cos 104 + cos 14)

             W = 1,049 10⁹ J

23
In order for a 12 Volt power source
to produce a current of 0.085 amps,
a resistance of...
[?] Ohms is needed.
Enter
Haven't learned this yet.

Answers

Answer:

141.18 ohms

Explanation:

From the question given above, the following data were obtained:

Voltage (V) = 12

Current (I) = 0.085 A

Resistance (R) =?

The resistance needed can be obtained as follow:

V = IR

12 = 0.085 × R

Divide both side by 0.085

R = 12 / 0.085

R = 141.18 ohms

Therefore, a resistor of resistance 141.18 ohms is needed.

Rhodium is in period 5 of the periodic table. What does this tell you about this element

Answers

Answer:

. It is an extraordinarily rare, silvery-white, hard, corrosion-resistant, and chemically inert transition metal. It is a noble metal and a member of the platinum group.

Explanation:

PLEASE HELP WILL GIVE BRALIEST

12. A bird flies 10 m in 2 seconds. What is its speed?


13. A plane takes 8 hours to fly 5000 km. What is its speed?


14. When given a motion graph, how can you tell if it’s a speed graph or acceleration graph?

Answers

Answer:

12: If the bird flies 10m in 2s, it's speed is then 10m/2s, which we can simplify giving us 5m/s

13: Flying 5000 km in eight hours means that it's flying at (5000 / 8)km/h, or 625km/h

14: A speed graph will not go below zero, an acceleration graph will.

1. Alexandra and Rachel are on a train that sounds a whistle at a constant frequency as
it leaves the train station. Compared to the sound emitted by the whistle, the sound that
the passengers standing on the platform hear has a frequency that is
a. lower, because the sound-wave fronts reach the platform at a frequency
lower than the frequency at which they are produced
b. lower, because the sound waves travel more slowly in the still air above the
platform than in the rushing air near the train
c. higher, because the sound-wave fronts reach the platform at a frequency
higher than the frequency at which they are produced
d. higher, because the sound waves travel faster in the still air above the
platform than in the rushing air near the train

Answers

Answer: the answer would be C trust me i took the test if its not that its b

hope that helps

Explanation: i took the test

answer:

a) lower because the sound-wave fronts reach the platform at a frequency lower than the frequency at which they are produced

explanation :3

If the train is leaving the train station, then the people who are standing on the platform would hear a sound with a lower frequency since the train is moving further away. ^^

On a 10 kg cart (shown below), the cart is brought up to speed with 50N of force for 7m, horizontally. At this point (A), the cart begins to experience an average frictional force of 15N throughout the ride.
Find:
a) The total energy at (A)
b) The velocity at (B)
c) The velocity at (C)
d) Can the cart make it to Point (D)? Why or why not?

Answers

Answer: Letter B! Is your answer

Time of the day when the Sun does not shine (___time)
N____N

Answers

I-
nighttime? So put night in the blank

A positive charge Q2 is uniformly distributed over a nonconducting disc of radius a which has a concentric circular hole of radius b. At the center of the hole there is another nonconducting disc of radius d where a charge Q1 is uniformly distributed.
a) Find the surface charge density of the disc with the hole σ2.
b) Find the surface charge density 01 of the disc of radius d.
c) Find the total charge enclosed by the circle of radius

Answers

Answer:

a)    σ = [tex]\frac{Q_1}{ a^2 - b^2}[/tex] ,  b)  σ = [tex]\frac{Q_2}{d^2}[/tex] , c) Q_ {total} = Q₁ + Q₂,  σ_ {net} = [tex]\frac{Q_1 + Q_2}{\pi \ a^2}[/tex]

Explanation:

a) The very useful concept of charge density is defined by

          σ = Q / A

In this case we have a circular disk

The are of a circle is

         A = π r²

in this case we have a hole in the center of radius r = b, so

         A_net = π r² - π r_ {hollow} ²

         A_ {net} = π (a² - b²)

whereby the density is

          σ = [tex]\frac{Q_1}{ a^2 - b^2}[/tex]

b) The density of the other disk is

          σ = Q₂ / A₂

          σ = [tex]\frac{Q_2}{d^2}[/tex]

c) The total waxed load is requested by the larger circle

           Q_ {total} = Q₁ + Q₂

the net charge density, in the whole system is

          σ = [tex]\frac{Q_{total} }{ A_{total} }[/tex]

the area  is

          A_{total} = π a²

since the other circle is inside, we are ignoring the space between the two circles

          σ_ {net} = [tex]\frac{Q_1 + Q_2}{\pi \ a^2}[/tex]

What is diffraction of light

Answers

Answer:

According to "http://ww2010.atmos.uiuc.edu"  Diffraction is the slight bending of light as it passes around the edge of an object.

Some examples of Light Defraction would be..

-CD reflecting rainbow colours

-Sun appears red during sunset

-From the shadow of an object

Energy is transferred through a solid
by if there is a
between the ends of it.
Liquids and solids transfer energy
by because the particles can
Energy is transferred much
through an insulator
than it is through a conductor.
Tore

Answers

Answer:

Conduction is the transfer of thermal energy through direct contact between particles of a substance, without moving the particles to a new location. Usually occurs in solids. When heat is supplied to one end, molecules at that end start to move more quickly.

Explanation:

Conduction is the transfer of heat and electricity through a material or surface. Generally, metals are good conductors of heat and electricity.

What is Conduction?

Conduction is the process through which heat energy is transmitted through the collisions which occur between neighboring atoms or molecules in a system. Conduction occurs more readily in the solids and liquid substances, where the particles are closer together than that of the gases, where the particles are further apart from each other.

Metals are good conductors of heat and electricity as they contain valence electrons and charge whereas non-metals are bad or poor conductors of heat and electricity as these elements does not contain valence electrons.

Learn more about Conduction here:

https://brainly.com/question/12136944

#SPJ2

As an admirer of Thomas Young, you perform a double-slit experiment in his honor. You set your slits 1.03 mm apart and position your screen 3.19 m from the slits. Although Young had to struggle to achieve a monochromatic light beam of sufficient intensity, you simply turn on a laser with a wavelength of 641 nm . How far on the screen are the first bright fringe and the second dark fringe from the central bright fringe

Answers

Answer:

Δx = distance between central bright fringe and first bright fringe = 19.85 x 10⁻⁴ m = 1.985 mm

distance between central bright fringe and second dark fringe = 2.978 mm

Explanation:

We have the following data:

λ = wavelength of light = 641 nm = 6.41 x 10⁷ m

L = Distance of Screen from slits = 3.19 m

d = slit separation = 1.03 mm = 1.03 x 10⁻³ m

Δx = distance between consecutive bright fringes = fringe spacing = ?

Using formula:

[tex]\Delta x = \frac{\lambda L}{d}\\\\\Delta x = \frac{(6.41\ x\ 10^{-7}\ m)(3.19\ m)}{1.03\ x\ 10^{-3}\ m}[/tex]

Δx = distance between central bright fringe and first bright fringe = 19.85 x 10⁻⁴ m = 1.985 mm

distance between central bright fringe and second dark fringe = 1.5Δx

distance between central bright fringe and second dark fringe = (1.5)(1.985 mm)

distance between central bright fringe and second dark fringe = 2.978 mm

The rods, which number over 100 million, can only be activated by a certain range of wavelengths, but they do not pass any color information to the brain. In other words, they note differences in shades of grey (from black to white) and are responsible for a person's ability to see in dim light. Cones, which number around 6 million, give us color vision. Cones come in three different kinds: 64%% of cones are sensitive to long wavelengths of visible light (toward the red end of the spectrum), 32%% are sensitive to medium wavelengths, and the remaining 2%% are sensitive to short wavelengths (toward the blue end of the spectrum). Colors are differentiated on the basis of the extent to which visible light stimulates each kind of cone.
Do rods have their peak sensitivity at a higher or lower frequency than cones?
a) Higher
b) Lower

Answers

Answer:

The correct answer is a

peak sensitivity is much higher for cones

Explanation:

After reading this interesting problem, where it gives a good description of the types of photoreceptor cells that exist in the eyes

The Cone has its name because of the shape of a cone that has this shape that allows to perceive very small amounts of intensity

The Canes have the shape of a cane and are filled with a substance that is sensitive to color colors, but they need a greater intensity of light to be activated, for which reason they work in the daytime, when it gets dark the intensity of the light is insufficient to activate these cells and the only ones that send information to the brains are the cones.

With this explanation it is clear that cones have high sensitivity at all frequencies and rods have low to medium sensitivity at specific frequencies.

Therefore peak sensitivity is much higher for cones

The correct answer is a

What would happen if the molecules in a sample moving entirely ?

Answers

Answer:

Molecular scale. The story begins a long time ago  

when the idea that molecules are in constant motion  

was first discovered. Part of the evidence that you can  

see in everyday life was discovered by Robert Brown  

about 150 years ago when he used a microscope to  

watch how tiny dust particles move.

So how fast do molecules move? It all depends upon  

the molecule and its state: molecules in a solid state  

move slower than in a liquid state, and much slower  

than gas molecules. One estimate puts gas molecules  

in the range of 1,100 mph at room temperature. Cool  

them down to almost absolute zero and they slow  

down to less than 0.1 mph (slower than the average  

couch potato). The fact that they are always moving  

makes it a challenge to see molecules and make stuff  

out of them, but it’s a challenge that scientists  

work hard to figure out.

Explanation:

g 1. To see why an MRI utilizes iron to increase the magnetic field created by a coil, calculate the current needed in a 400-loop-per-meter circular coil 0.660 m in radius to create a 1.20-T field (typical of an MRI instrument) at its center with no iron present. The magnetic field of a proton is approximately like that of a circular current loop in radius carrying . What is the field at the

Answers

Answer:

I = 2387.32 A

Explanation:

Given that,

Number of turns in the loop, N = 400

The radius of the circular coil, r = 0.66 m

The magnetic field inside the MRI, B = 1.2 T

We need to find the current in the loop. The magnetic field inside the solenoid is given by :

[tex]B=\mu_o NI\\\\I=\dfrac{B}{\mu_o N}\\\\I=\dfrac{1.2}{4\pi \times 10^{-7}\times 400}\\\\I=2387.32\ A[/tex]

So, the required current is equal to 2387.32 A.

help me pls
An object accelerates if it:

a.) changes the direction of its velocity but not the magnitude

b.)changes the magnitude of the velocity but not the direction

c.)changes its speed

d.) all of the above

e.) none of the above

Answers

Answer:

D

Explanation:

A planet of mass M has a moon of mass m in a circular orbit of radius R. An object is placed between the planet and the moon on the line joining the center of the planet to the center of the moon so that the net gravitational force on the object is zero. How far is the object placed from the center of the planet

Answers

Answer:

r =[tex]\frac{ 1 \pm \sqrt{ \frac{m}{M} } }{1 - \frac{m}{M} }[/tex]

Explanation:

Let's apply the universal gravitation law to the body (c), we use the indications 1 for the planet and 2 for the moon

          ∑ F = 0

           -F_{1c} + F_{2c} = 0

             F_{1c} = F_{2c}

let's write the force equations

             [tex]G \frac{m_c M}{r^2} = G \frac{m_c m}{(d-r)^2}[/tex]

where d is the distance between the planet and the moon.

              [tex]\frac{M}{r^2} = \frac{m}{(d-r)^2}[/tex]

             (d-r)² = [tex]\frac{m}{M} \ \ r^2[/tex]  

              d² - 2rd + r² = \frac{m}{M} \ \ r^2

              d² - 2rd + r² (1 - [tex]\frac{m}{M}[/tex]) = 0

              (1 - [tex]\frac{m}{M}[/tex])  r² - 2d r + d² = 0

we solve the second degree equation

              r = [2d ± [tex]\sqrt{ 4d^2 - 4 ( 1 - \frac{m}{M} ) }[/tex] ] / 2 (1- [tex]\frac{m}{M}[/tex])

              r = [2d ±  2d [tex]\sqrt{ \frac{m}{M} }[/tex]] / 2d (1- [tex]\frac{m}{M}[/tex])

              r =[tex]\frac{ 1 \pm \sqrt{ \frac{m}{M} } }{1 - \frac{m}{M} }[/tex]

there are two points for which the gravitational force is zero

The distance between object from planet will be "[tex]\frac{R}{[1+\sqrt{\frac{m}{M} } ]}[/tex]".

According to the question,

Let,

Object is "x" m from planet center = R - xGravitational force = 0Mass of object = m₁

As we know,

→ [tex]Prerequisites-Gravitational \ force = \frac{GMm}{r^2}[/tex]

Now,

→ [tex]\frac{GMm_1}{x^2} = \frac{Gmm_1}{(R-x)^2}[/tex]

→ [tex]\frac{(R-x)^2}{x^2} = \frac{m}{M}[/tex]

→     [tex]\frac{R-x}{x} =\sqrt{\frac{m}{M} }[/tex]

→          [tex]x = \frac{R}{[1+ \sqrt{\frac{m}{M} } ]}[/tex]

Thus the answer above is appropriate.          

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