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strength or energy as an attribute of physical action or movement.

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Earth on the stuff contained in the object.

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the rate at which someone or something is able to move or operate.

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Speed is a way of measuring how quickly something is moving or being done, or something moving fast.

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a vehicle's capacity to gain speed within a short time.

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Speed is a constant 40 km/hr, but velocity changes every time you change direction.

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the action or process of moving or being moved.

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Newton's Laws of Motion with Real Life Examples.

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Laws of Motion - examples, body, process, Earth, energy, reaction, air, change

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As the arrow continues to move, it will slow down. The arrow is passing through air, whose molecules rub against the arrow, causing it to lose speed. In addition, the arrow begins to change direction, moving toward Earth because of gravitational forces.

# data[].attributes.body
a basis or standard for evaluation, assessment, or comparison; a criterion.

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In either situation motion is when an object changes position compared to a reference point.

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Balance forces are two forces acting in opposite directions on an object, and equal in size.
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This is an  of balanced forces. The force exerted by each person is equal, but they are pushing in opposite directions

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A net force is defined as the sum of all the forces acting on an object.
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In the diagram at left, the net force is 5 Newtons to the right.

# data[].attributes.body
the total distance traveled divided by the total time elapsed.

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The average speed of an object is the total distance traveled by the object divided by the elapsed time to cover that distance.

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Questions on Time, Speed & Distance are asked in Quantitative Aptitude or Numerical Ability sections of exams like SBI Clerk, SBI PO, SSC CGL, Railway RRB, LIC AAO, IBPS Clerk, IBPS RRB, IBPS PO etc. Often times, these questions have to do with finding out Average Speed. In order to calculate Average Speed, we must understand the concept of speed and why it doesn't work like your regular averages.

Average Speed looks like a simple enough topic, but somehow the rules of your regular averages don't apply. The term 'Average' then becomes confusing. We all know the formula for average we learnt in school:

But in the case of Average Speed it is not equal to average of all the speeds. Then how do we calculate it? Let's take a look.

Average Speed

The average speed of an object tells you the (average) rate at which it covers a certain distance while its speed at different times may have been different. Average speed is a measure of the distance traveled in a given period of time; it is sometimes referred to as the distance per time ratio.

The Average Speed formula helps you to calculate the average speed for the set of different distances d ₁, d ₂..... d n if their corresponding different time intervals t ₁, t ₂,....t n are given.

Let us look at this using a problem. Say, a car travels at S ₁ mph on a trip in t ₁ time and at S ₂ mph on return trip in t 2 time. What is its average speed for the entire trip?

For this type of problems, don't fall in the trap of just averaging the 2 speeds even if the times t ₁ and t ₂ are the same. The overall average speed is NOT .

Total average speed is simply = Total distance / Total time

Tip: This is for 2 speeds. You can extend this to 3 speeds like this:

Notice, that this then becomes the formula for harmonic mean. Average speed is not the arithmetic mean but the harmonic mean.

Example of Average Speed

Let us understand this concept using an example.

Q. In travelling from Mumbai to Goa, Moumita drove for 1 hour at 50 mph and for 3 hours at 60 mph. What was her average speed for the whole trip?

1) 50.0 mph

2) 53.5 mph

3) 55.5 mph

4) 56.0 mph

5) 57.5 mph
Ans: 5) 57.5 mph
Solution: As we know that, Distance = Speed × Time

So, in 1 hour, distance covered = 50 × 1 = 50 miles

In next 3 hours, distance covered = 60 × 3 = 180 miles

Total distance covered = 50 + 180 = 230 miles

Total Time = 1 + 3 = 4 hrs

We know that,

⇒ Avg. Speed = 230/4 = 57.5 mph

Note: Here Average speed will not be simply (50+60)/2 = 55.5mph

Now Try It Yourself

A car travels the first one-third of a certain distance with a speed of 10 km/hr, the next one-third distance with a speed of 20 km/hr, the last one-third distance with a speed of 60 km/hr. The average speed of the car for the whole journey is:
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# data[].attributes.attachment_link.description
Questions on Time, Speed & Distance are asked in Quantitative Aptitude or Numerical Ability sections of exams like SBI Clerk, SBI PO, SSC CGL, Railway RRB, LIC AAO, IBPS Clerk, IBPS RRB, IBPS PO etc. Often times, these questions have to do with finding out Average Speed.

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Static friction is the friction that exists between a stationary object and the surface on which it's resting.
google.com

The reason is static friction Static friction is the friction that exists between a stationary object and the surface on which it's resting

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Friction is one of the most important forces that are held responsible for movement on the surface of Earth or in other words we can say that indirectly this is the force which has made the life possible on Earth. As a common mindset, we know that friction is the resisting force that is always available when two or more than two bodies collide. In easy words, friction is the force that works as a hindrance or as opposed to the motion of the object. There are four major types of friction, static friction, kinetic friction, rolling friction and fluid friction. Static Friction is the type of friction between the bodies which keeps the object at rest, whereas when the force acting against friction overcomes static friction and body comes in motion, kinetic friction is the type of friction which slows down the moving object. The magnitude of static friction is always more than the kinetic friction. It means that more force is required to overcome the static friction or to make the object move than in the kinetic friction where the force applied is to make object keep moving as it is already in motion.

Comparison Chart

Definition with Explanation
Static Friction is the type of friction between the bodies which keeps the object at rest.

When the force acting against friction overcomes static friction and body comes in motion, kinetic friction is the type of friction which slows down the moving object.

What is Static Friction?

It is the type of friction between the bodies which keeps the object at rest. When you apply a force on the table to drag it and fail several times, the force making you fail all these times is the static friction as it works as the opposer or the antagonist of the motion. To beat or cut off this static friction, what you do is that you put in more of your force, and finally, the table gets moving. When the objects on the rest start moving, that means static friction has reached its maximum value. If an object is in the state of rest and no external force is acting upon against it to make it in the motion, the static friction is zero as much the external force increases the static friction increases, and at one stage the static friction reaches its maximum value and objects starts moving. The static friction depends upon μsμs (coefficient of static friction) and N (net normal reaction of the body). The static friction can either be less or equal to the product of μsμs (coefficient of static friction) and N (net normal reaction of the body). The static friction is exactly equal to the external force being put on the object and is always opposite to the direction of motion.

What is Kinetic Friction?

When a body comes in motion after overcoming the static friction or the static friction reaches its maximum value, the force which works as opposed and slows down the moving object is called the kinetic friction. The magnitude of kinetic friction is low as compare to the magnitude of static friction that is why it works as a hindrance in between the object but didn't put it to the rest state it just slows down the motion of the moving object. When you apply a force on the table to drag it and fail several times, the force making you fail all these times is the static friction as it works as the opposer or the antagonist of the motion. To beat or cut off this static friction, what you do is that you put in more of your force, and finally, the table gets moving, and when you try to drag the table more quickly, you will feel a certain force working as a hindrance and slowing it down. The force acting at that time will be the kinetic friction. The formula for Magnitude of kinetic frictional force f k = μkμk N, where μkμk is the coefficient of kinetic frictional force, and N is the net normal reaction on the body.

Static vs. Kinetic Friction

Static Friction is the type of friction between the bodies which keeps the object at rest, whereas Static Friction is the type of friction between the bodies which keeps the object at rest.

The magnitude of static friction is always more than the kinetic friction.

Static Friction can be zero, but Kinetic friction can never be zero.

Explanatory Video

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Static Friction vs. Kinetic Friction: What's the Difference?

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Friction is one of the most important forces that are held responsible for movement on the surface of Earth or in other words we can say that indirectly this is the force which has made the life possible on Earth.

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The friction of rest or quiescence, "statically friction," is greater than that of motion, or " kinetic friction."
http://www.dictionary.com/

Specific of sliding friction include:
Rubbing both hands together to create heat.

# data[].attributes.attachment_link.readable_text
Friction is one of the most important forces that are held responsible for movement on the surface of Earth or in other words we can say that indirectly this is the force which has made the life possible on Earth. As a common mindset, we know that friction is the resisting force that is always available when two or more than two bodies collide. In easy words, friction is the force that works as a hindrance or as opposed to the motion of the object. There are four major types of friction, static friction, kinetic friction, rolling friction and fluid friction. Static Friction is the type of friction between the bodies which keeps the object at rest, whereas when the force acting against friction overcomes static friction and body comes in motion, kinetic friction is the type of friction which slows down the moving object. The magnitude of static friction is always more than the kinetic friction. It means that more force is required to overcome the static friction or to make the object move than in the kinetic friction where the force applied is to make object keep moving as it is already in motion.

Comparison Chart

Definition with Explanation
Static Friction is the type of friction between the bodies which keeps the object at rest.

When the force acting against friction overcomes static friction and body comes in motion, kinetic friction is the type of friction which slows down the moving object.

What is Static Friction?

It is the type of friction between the bodies which keeps the object at rest. When you apply a force on the table to drag it and fail several times, the force making you fail all these times is the static friction as it works as the opposer or the antagonist of the motion. To beat or cut off this static friction, what you do is that you put in more of your force, and finally, the table gets moving. When the objects on the rest start moving, that means static friction has reached its maximum value. If an object is in the state of rest and no external force is acting upon against it to make it in the motion, the static friction is zero as much the external force increases the static friction increases, and at one stage the static friction reaches its maximum value and objects starts moving. The static friction depends upon μsμs (coefficient of static friction) and N (net normal reaction of the body). The static friction can either be less or equal to the product of μsμs (coefficient of static friction) and N (net normal reaction of the body). The static friction is exactly equal to the external force being put on the object and is always opposite to the direction of motion.

What is Kinetic Friction?

When a body comes in motion after overcoming the static friction or the static friction reaches its maximum value, the force which works as opposed and slows down the moving object is called the kinetic friction. The magnitude of kinetic friction is low as compare to the magnitude of static friction that is why it works as a hindrance in between the object but didn't put it to the rest state it just slows down the motion of the moving object. When you apply a force on the table to drag it and fail several times, the force making you fail all these times is the static friction as it works as the opposer or the antagonist of the motion. To beat or cut off this static friction, what you do is that you put in more of your force, and finally, the table gets moving, and when you try to drag the table more quickly, you will feel a certain force working as a hindrance and slowing it down. The force acting at that time will be the kinetic friction. The formula for Magnitude of kinetic frictional force f k = μkμk N, where μkμk is the coefficient of kinetic frictional force, and N is the net normal reaction on the body.

Static vs. Kinetic Friction

Static Friction is the type of friction between the bodies which keeps the object at rest, whereas Static Friction is the type of friction between the bodies which keeps the object at rest.

The magnitude of static friction is always more than the kinetic friction.

Static Friction can be zero, but Kinetic friction can never be zero.

Explanatory Video

# data[].attributes.attachment_link.title
Static Friction vs. Kinetic Friction: What's the Difference?

# data[].attributes.attachment_link.description
Friction is one of the most important forces that are held responsible for movement on the surface of Earth or in other words we can say that indirectly this is the force which has made the life possible on Earth.

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surface resistance to relative motion, as of a body sliding or rolling.
http://www.dictionary.com/

because it give you more grep