A child is standing on the platform of a station, watching the trains.
.
A train travelling at 30 m/s takes 3 s to pass the child.
What is the length of the train?
A 10m
B 30 m
C 90 m
D 135 m

Answers

Answer 1
C. 90 m

30m per second... and it takes 3 seconds

3x30= 90
Answer 2
c 90 m
30 times 3 equals 90

Related Questions

If the ball rolls out of bounds on the sideline in soccer, what is the result?

a.Free Kick
b.Goal Kick
c.Throw-In
d.Corner Kick

Answers

the answer for this problem is C

Which type of wave interaction is shown in the diagram?
wave A
MAAAAA
wave B
MAAAA
wave A + B
PAMA
A. Destructive interference
B. Diffraction subtraction
C. Diffraction gradient
D. Constructive interference

Answers

Answer: Constructive interference

Explanation: Just took the test

You toss a walnut at a speed of 15.0 m/s at an angle of 50.0∘ above the horizontal. The launch point is on the roof of a building that is 20.0 m above the ground.


a)How long after it is launched does the walnut reach the ground?

b)How far does the walnut travel horizontally from launch point to landing point?

c) What are the horizontal and vertical components of the walnut’s velocity just before it reaches the ground? Suppose that the +y-axis is directed upward and the +x-axis is directed horizontally from the launch point toward the landing point.

Answers

Answer:

a.3.51s

b.33.8m

c. 9.64,-22.9

Explanation:

(a) The time taken be "3.5083 sec".

(b) The distance will be "33.82 m".

(c) The horizontal and vertical components be "9.64 m/s and -22.89 m/s".

Velocity and Direction

According to the question,

Speed, V₀x = 15 Cos (50.0°)

                   = 9.64 m/s

            V₀y = 15 Sin (50.0°)

                   = 11.49 m/s

Vertical displacement = -20.0 m

(a) We know the relation between displacement, time and acceleration

→  y = vt + [tex]\frac{1}{2}[/tex]at²

By substituting the values,

→ -20.0 = 11.49 t - 4.9 t²

  4.9 t² - 11.49 t - 20.0 = 0

                                   t = [tex]\frac{11.49 + \sqrt{132.02+392} }{9.8}[/tex]

                                     = [tex]\frac{11.49 + 22.89}{9.8}[/tex]

                                     = 3.5083 sec

(b) We know the formula,

Distance = Speed × Time

or,

→ X = 9.64 t

      = 9.64 × 3.5083

      = 33.82 m

(c) Again by using the above relation, we get

    Vx = V₀x

          = 9.64 m/s

    Vy = V₀y - gt

By substituting the values,

          = 11.49 - 9.8 × 3.5083

          = 11.49 - 34.38

          = -22.89 m/s

Thus the response above is correct.

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the force has to be specified both in terms of its magnitude as well as its direction true or false? ​

Answers

Anwser

The strength of a force is usually expressed by its magnitude. We have also to specify the direction in which a force acts.

Yes it is about the force and stuff

Rae has just heard a loud crash from her garage. The impact of the sound wave bouncing against her eardrum sets off a chain reaction through the three tiny bones in the middle ear, called the:

Answers

Answer:

Hammer

Anvil

Stirrup

Explanation:

The three tiny bones in the ear drum are:

Hammer, this is also known as malleus and it is attached to the eardrum

Anvil, this is also called incus and it found with the chain of bones in the middle ear.

Stirrup, also known as stapes and it attached to the membrane covered opening that connects the middle ear with the inner ear.

Use the drawing below to answer the following question.
1 kg
10 kg
20 kg
50 kg
All of the boxes shown above can slide easily. Which box will move farthest if each is
struck with the same amount of force?
A.
the 1-kg box
B. the 10-kg box
C. the 20-kg box
D. the 50-kg box

Answers

Answer:

A

Explanation:

Force =  mass x acceleration

if the force is constant for each of the boxes, the smaller a boxes mass the greater its acceleration while the force is applied

Therefore the smaller box will have a greater initial velocity and will slide the furthest before it stops.

Robert hook used an early microscope to observed a cork sample. How did this help contribute to cell theory?

Answers

Answer:

Robert Hooke used an early microscope to observe a cork sample. How did this help contribute to cell theory? It helped to show that cells contain water. ... It helped to show that some cells are visible to the naked eye.

Explanation:

If your teacher checks if it was copied just put it in your on words

Pleaseeeeeeeeeeeeeeeeeee

Answers

Definitely b
Just makes the most sense

what is kinetic energy​

Answers

Answer:

Kinetic energy is the movement of objects based on their mass and motion

Explanation:

A form of energy that an object or a particle has by reason of its motion. kinectic energy is a property of a moving object or particle and depends not only on its motion but also on its mass

PLEASE HELP SOMEONE ASAPAPP!P

Answers

Balanced
Unbalanced
Balanced
Balanced (I think)

6 N M 8N
What is the net force?​

Answers

Answer:

14 Newtons

Explanation:

6N + 8N = 14N

how to make, and put out a fire in the SAFEST way.

Answers

Answer:

Surround the area of fire with water so the fire cant spread.  And after, pour water on the fire.  Always surround the fire first to stop it from spreading.  When handling fire there are no specific "safe" ways but this is probably the best way to go orby fire estinguisher which is probably the easiest if you have one nearby which usually you should or do have.

I hope I helped.  Pls mark brianliest if it helps.  Bye, take care:)

Fill in the blanks:
1. When a spring is pulled, the _____ is proportional to the ______ ( called ____ law.
2.Weight is the force of ____ on an object due to the pull of the _____
3. Weights and other forces are measured in ______
4. Here on Earth, the pull of gravity on a mass of 1 kg is ______ Newtons
5. Weight is measured by a _____ balance and _______ from place to place
6. Newton's first law says: every mass stays at _______ or moves at constant _______ in a _______ line unless a resultant _______ acts on it
7. To move in a _______ orbit, an object must have a _______ force on it

Answers

Answer:

st8tif7u

Explanation:

t996w4sia74a85e8srz

What is the current if 4C of charge passes in 2 s?

Answers

Answer:

I hope 2 amperes of current passes

A book is sitting on the dashboard of a car that is stopped at a traffic light as the car starts to move forward the book slides backward off the dashboard what does the book actually do

Answers

Answer:

The book remained in its state of rest before the car started to move forward as no direct force acted on it.

Explanation:

According to Newton's first law of motion, a body will continue in its present state of rest, or if it is in motion, will continue to move with uniform speed in a straight line unless aced upon by an external force. This tendency of a body to remain in its state of reset or uniform motion in a straight line is known as inertia and is directly proportional to the mass of the body. The more massive a body, the more inertia it possesses. Thus Newton's first law is also known as the law of inertia.

Considering the case of the book on the dashboard of a stationary car which suddenly starts to move. While the car is stopped at the traffic light, the dashboard where the book sits and the book are both at rest. When the car begins to move forward, the dashboard moves forward with it. However as the book is not a part of the car, no force is directly acting on it, so the book so it stays at rest due to its inertia.

Therefore, as the car is moving forward, the stationary book appears to move backward from the reference point of the car, sliding off the dashboard.

Select all that apply. According to scientists, the distribution of volcanoes throughout the world…

Forms a specific pattern across fault lines
Corresponds to plate boundaries
Is constantly changing and shifting
Is fairly even and widespread

Answers

Corresponds to plate boundaries
Is constantly changing and shifting

Answer:

Corresponds to plate boundaries

Is constantly changing and shifting

Explanation:

another A b c or d about the earth...

Answers

Answer:

B seismic wave

A weight of 4.0 N is used to extend a spring. The extension of the spring is 0.06 m. (i) Calculate the spring constant, k, of the spring.

(ii) State what measurements should be made to determine the extension of the spring produced by the 4.0 N weight.

Answers

Answer:

See explanation

Explanation:

Hookes law states that; the displacement due to a stretching force is directly proportional to the magnitude of the deforming force.

F = ke

F = deforming force

k = force constant

e = extention

k = F/e

k = 4N/0.06 m= 66.67 Nm^-1

To determine the extension of the spring produced by the 4.0 N weight

1) We measure the original length of the spring

2) We measure the length after hanging the 4 N mass

3) Subtract the new length from the original length to determine the extention.

You would like to know whether silicon will float in mercury and you know that can determine this based on their densities. Unfortunately, you have the density of mercury in units of kilogrammeter3 and the density of silicon in other units: 2.33 gramcentimeter3. You decide to convert the density of silicon into units of kilogrammeter3 to perform the comparison. By which combination of conversion factors will you multiply 2.33 gramcentimeter3 to perform the unit conversion?

Answers

Answer:

The fourth one

Explanation:

It's the only one to represent volume (cm³ vs. m³) and have kilograms in the denominator.

Have a wonderful weekend!

If we want to convert the density of the silicon from  2.33 gram/ centimeter3 to kilogram /meter3 unit we have to perform the operation

(1 kilogram/ 10³ grams) ×(1 centimeter/10⁻² meters)×(1 centimeter/10⁻² meters)×(1 centimeter/10⁻² meters)

Therefore the correct answer is option B.

What is density?

It can be defined as the mass of any object or body per unit volume of the particular object or body. Generally, it is expressed as in gram per cm³ or kilogram per meter³.

As given in the problem we have to convert the density of the silicon from  2.33 gram/ centimeter3 to kilogram /meter3 unit

1 kilograms = 1000 grams

1 meter = 100 cm

2.33 gram/ centimeter3 = 2.33×10 ⁻³kilogram / 10 ⁻⁶meter3 unit

                                       = 2.33×10³kilogram / 10 ⁻⁶meter3 unit

Thus, the correct answer is option B.

Learn more about density from here,

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Need help ASAP
Thanks + BRAINLIST only for correct answer

1.Cell phones convert sound waves into______waves.
-light waves
-sound waves
-radio waves

2.Electromagnetic waves used in cell phone communications are called?
-microwave
-radio wave
-infrared
-all of the above

3.To send out a radio signal far and wide...it is called?
-broadcast
-casting
-antenna

Answers

Answer:

answer my question

Explanation:

Mhm yeah correct I think yeah yeah lol

Gravitational force acts on all objects in proportion to their masses. Why then, a heavy object does not fall faster than a light object?

Plss help!!!!

Answers

Answer:

This is because the acceleration of objects due to gravity is independent of the mass of the object and is constant for all objects, therefore, all objects fall with the same speed.

Explanation:

The weight of an object or force of gravity acting on an object on the surface of earth is a product of its mass and acceleration due to gravity.

Mathematically, w = mg

where, m=mass of the object; g = acceleration due to gravity

Also, from newton's law of gravitation, gravitational force on the object ,F = GMm/r²

where G is the gravitational constant; M is mass of Earth; m is mass of object; r is the distance of separation between the object and the center of mass of the earth which is approximately the radius of earth.

Since the weight of an object is equal to the force of gravitation acting on it

W = F

mg = GMm/r²

g = GM/r²

The expression above is that of the relationship between the force of gravity acting on a body on the earth's surface, the weight of that body and the acceleration due to gravity, g.

It can be seen that the acceleration due to gravity g is independent of the mass of the object. Therefore, the acceleration of objects due to gravity is constant for all objects and all objects fall with the same speed.

Answer:

The time of fall of an object is dependent only on the height of fall for a given acceleration due to gravity and it is independent of the object's mass

Explanation:

The gravitational force acting on an object on Earth can be observed as the weight, 'W', of the object which is a function of the mass, 'm', of the object and the relationship between the gravitational force and the mass of the object is given as follows;

W = m × g

Where;

g = The acceleration due to gravitational force = Constant

The relationship between the speed, 'u', and therefore, the time, 't', with which an object falls, the distance or height of fall, 'h', and the acceleration of the motion, 'g' is given as follows;

h = u·t + 1/2·g·t²

Given that the initial velocity of the object, 'u', of the object allowed to fall is u = 0 m/s, we have;

h = u·t + 1/2·g·t² = 0 × t + 1/2·g·t²

h = 0 × t + 1/2·g·t² = 1/2·g·t²

h = 1/2·g·t²

t² = 2·h/g

t = √(2·h/g)

Therefore, the time, 't', it takes every object to fall from a height, 'h', is dependent only on the height, 'h', for a given acceleration due to gravity, 'g' and it is independent of the mass, 'm', of the object.

A spring has a spring constant k = 20N/cm. What load is needed to produce an extension of 2.5cm?



ASAP please !

Answers

Answer:

50 N

Explanation:

We are given;

Spring constant; K = 20N/cm

Extension; Δx = 2.5 cm

We want to find the load which is the force. This is gotten from the equation;

F = k•Δx

F = 20 × 2.5

F = 50 N

Therefore the load needed is 50 N.

Georgia drops a brick from the top of an 80.0 m building. What is the velocity of the brick when it hits the ground?

Answers

Answer:

the velocity of the brick when it hits the ground is 39.60 m/s

Explanation:

Given;

height through which the ball is dropped, h = 80.0 m

the initial velocity of the brick, u = 0

The final velocity of the brick when it hits the ground is calculated as;

v² = u² + 2gh

v² = 0 + 2 x 9.8 x 80

v² = 1568

v = √1568

v = 39.60 m/s

Therefore, the velocity of the brick when it hits the ground is 39.60 m/s

A boat has a porthole window, of area 0.00849 m^2, 6.25 m below the surface. The density of sea water is 1027 kg/m^3. The air inside the boat is at 1 atm. What is the net force on the window?

Answers

Answer:

[tex]325.65\ \text{N}[/tex] outward.

Explanation:

[tex]\rho[/tex] = Density of water = [tex]1027\ \text{kg/m}^3[/tex]

g = Acceleration due to gravity = [tex]9.81\ \text{m/s}^2[/tex]

h = Height of the water = 6.25 m

A = Area of the window = [tex]0.00849\ \text{m}^2[/tex]

[tex]P_i[/tex] = Internal pressure of the boat = [tex]1\ \text{atm}=101325\ \text{Pa}[/tex]

Pressure by the water on the window

[tex]P=\rho gh\\\Rightarrow P=1027\times 9.81\times 6.25\\\Rightarrow P=62967.9375\ \text{Pa}[/tex]

Net pressure on the window

[tex]P_n=P-P_i=62967.9375-101325=-38357.0625\ \text{Pa}[/tex]

Force is given by

[tex]F=P_nA\\\Rightarrow F=-38357.0625\times 0.00849\\\Rightarrow F=-325.651460625\ \text{N}[/tex]

Net force on the window is [tex]325.65\ \text{N}[/tex] outward.

Answer: 534.6 N

Explanation:

This answer works for Acellus!

PLS ANSWER FAST WILL GIVE BRAINLY TIMED TEST


use the equation solving a= F divided by M


Also use metres per second squared [m/s2]



A loaded coal wagon with a total mass of 20, 000 kg is pushed by a force of 300,000 N. What was the wagon's acceleration?

Answers

a=F/m
a=(3000000)/(20000)
a=15 m/s^2

Describe the buoyant force acting on the Lucia before the torpedo attack.

Answers

Answer:

Explanation: positive

how do you fix a broken foot
my sister is in literal tears and i dont have a phone and
our parents are out of the house rn

Answers

Go to your neighbor house and calll the hospital they’ll help or you can call your parent’s

Which green shape is the least reactive?

(Subjective is actually science)​

Answers

Answer:

the green smiley face

Explanation:

its is farthest from the right

and as stated on the chart, the farther left, the more reactive

less stable=more reactive

more stable= less reactive

The green smiley face

3. Why is static electricity not useful as a power

source?

A. Because electrons aren't transferred in bursts of

static electricity

B. Because all energy is released at once in static

electricity

C. Because static electricity is not a real form of

electricity

D. Because static electricity only occurs in lightning

Answers

The answer is B, because all energy is released at once in static electricity.

There’s a quizlet that mentions these questions, if you are having trouble. I’d suggest to give them a look.

Static electricity is not useful as a power source primarily because it releases all of its energy at once rather than providing a continuous and controlled flow of electrical energy. The correct answer is B.

When static electricity is discharged, such as in a spark or a sudden discharge of stored charge, it happens in a rapid and uncontrolled manner, resulting in a brief burst of energy rather than a steady and sustained flow.

Power sources typically require a continuous and controllable flow of electrical energy to be useful for various applications. Static electricity, in its nature, does not provide this continuous flow but instead releases energy in an instantaneous manner. Therefore, it is not suitable for most practical power needs and applications.

Option A is not correct because electrons can be transferred in bursts of static electricity. Option C is not correct because static electricity is a real form of electricity, even though it has unique characteristics. Option D is not correct because static electricity can occur in various circumstances, not just in lightning.

Therefore, Static electricity is not useful as a power source primarily because it releases all of its energy at once rather than providing a continuous and controlled flow of electrical energy. The correct answer is B.

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7. The sketch shows a painter standing on a

scaffold that is supported by two ropes. The

person weighs 500 N and the force of each

rope is 400 N. Calculate the weight of the

scaffold.

Fr

Answers

Answer:

300N

Explanation:

From the question

Weight of painter = 500N

Weight of scaffold = x

Weight of painter + weight of scaffold = 2* 400 (since they are supported by two ropes)

Substitute

500 + x = 2(400)

500+x = 800

x =  800-500

x = 300N

Hence the weight of the  scaffold is 300N

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