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# Feedback Comments on Force

by Ron Kurtus

A total of 162 comments and questions have been sent in. They are listed according to date.

You can read them to further your understanding of the subject.

## List of next 10 letters

### Country

Forces Forces involved in rocket launch India

Centripetal Force Work when traveling in a circle Pakistan

Characteristics of Force Who is the father of physics? Ghana

Forces Passenger in accelerating vehicle UK

Characteristics of Force What type of force does a knife apply? Nigeria

Centrifugal Force is Not Real A real force requires acceleration Pakistan

Forces A pulling force is impossible Canada

Force and Motion How does a force come? India

Characteristics of Force How can i measure a force on a building? Nigeria

Forces Wants Newton's Third Law explained Pakistan

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First 10 letters

## Forces involved in rocket launch

Topic: Forces

### Question

November 20, 2011

A rocket has been fired upwards to launch a satellite in its orbit. Name the two forces acting on the rocket immediately after leaving the launching pad.

vinod - India

22186

### Answer

There is the force of the rocket engine pushing it upward. Then there is the inertial force resisting acceleration. There is also air resistance force and the force of gravity.

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## Work when traveling in a circle

Topic: Centripetal Force

### Question

November 5, 2011

sir why work done is zero when moving in a circle? explain briefly

owais - Pakistan

22140

### Answer

Work is defined as a force overcoming a resistance times the distance traveled. The force and distance traveled are in the same line.

When the force is perpendicular to the line of motion, such as when spinning an object on a string or the effect of gravitation from the Sun on the Earth, there is no motion in line with the force. They remain at the same distance, and thus the work done is zero.

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## Who is the father of physics?

Topic: Characteristics of Force

### Question

August 9, 2011

who is the father of physics?

jennifer - Ghana

21874

### Answer

Each country has had scientists and physicists who have made valuable contributions. The English-speaking countries often say that Isaac Newton was the father of physics. However, there were many good scientists before him that led the way. Other countries would claim their person was the father.

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## Passenger in accelerating vehicle

Topic: Forces

### Question

July 6, 2011

Passenger who is seated in a vehicle is travelling with an acceleration 'a' . Explain the forces of the passenger who is seated in the vehicle and other observer standing outside of the car observes

- UK

21792

### Answer

The force pushing the passenger toward the seat back is F = ma, where "m" is his mass and "a" is the acceleration of the vehicle. Since the person is seated, he is not moving with respect to the vehicle. An outside observer cannot tell of any forces on the passenger, so he will simple the the passenger moving forward with the vehicle.

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## What type of force does a knife apply?

Topic: Characteristics of Force

### Question

April 8, 2011

I know that a pair of scissors or shears shears by a shearing force. What about when one is using a knife to cut an object, is shearing also actually taking place here; if not, then what? Must a force, such as a shearing force or of some other forms, cause a push or pull; can't it create internal stress or something else? If it can, shouldn't that broaden our orientation of what a force is?

Thank you very much for your anticipated response.

- Nigeria

21458

### Answer

A knife is considered a wedge, which is a simple machine. When you push on a knife with a given force, the resulting pressure is force divided by the applied area. Since the knife is very sharp, the cutting area is quite small, such that the pressure can cut into a material. Then the knife acts as a wedge to push apart the sides of the material.

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## A real force requires acceleration

Topic: Centrifugal Force is Not Real

### Question

April 8, 2011

Here u says centrifugal force isn't a real force Because a real force requires acceleration. How can centripetal force contain acceleration. Kindly explain.

Rahat - Pakistan

21453

### Answer

What they call a real force is what is caused by a physical push or a pull. It is like pushing on a door is a real force. It will accelerate the door.

But also, a property of matter is inertia that say matter tends to go in a straight line. If an object is caused to curve, there is the inertia force that tries to keep it going straight. That force is called a virtual force, because it is really a property of matter and not something external.

Changing directions is an acceleration and requires a force. Thus, swinging an object on a string accelerates the object by changing its direction.

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## A pulling force is impossible

Topic: Forces

### Question

February 11, 2011

Mysterious Force at a Distance is nonsense.

F=mA A Pulling Force is "Impossible" !

Giant Scientific Discovery

www.EinsteinGravity.com

AL - Canada

21183

### Answer

There are many examples of a force at a distance that have not been effectively explained. In some cases--like the attraction of opposite poles of the magnets--where you could say the magnetic field wraps around and pushes the magnets together, there are many others where pushing does not really make sense. However, it may be a matter of interpretation.

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## How does a force come?

Topic: Force and Motion

### Question

January 22, 2011

How force will come please answer me

ningappa - India

21056

### Answer

A force is a push or a pull. You can apply a force by pushing on something. Likewise, the wind or an explosion can apply a force.

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## How can i measure a force on a building?

Topic: Characteristics of Force

### Question

January 18, 2011

how can i measure a force on a story building

hamzat - Nigeria

21036

### Answer

Something has to cause the force on a building, whether it is gravity or wind or something else. That is the starting point for measuring the force.

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## Wants Newton's Third Law explained

Topic: Forces

### Question

December 10, 2010

sir first of all i thanks u because u make the web then every student can gain knowledge from its .but i have some problem so i am tell u that how is a newtons discoverd its 3lw and how is its use in our daily life plz tell us about clearly concept

vijay - Pakistan

20820

### Answer

Isaac Newton was a very observant scientist, such that he knows things Andrew some sharp conclusions. But also he was helped by the work of other scientists.

Newton's Third Law is called the action-reaction law. This law is useful when you row a boat, where the action of the oar pushes the boat for word as a reaction. Also, the hot air coming out of a jet engine pushes the aircraft forward.

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