26 votes

Why does "potential energy" have the word "potential" in it?

Because it has the potential to produce mechanical work.
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19 votes
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Why does "potential energy" have the word "potential" in it?

potential (adj.) Capable of being but not yet in existence; latent or undeveloped. The block is stationary and therefore not performing work. If the block never moves, the potential energy remains ...
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6 votes

Why does "potential energy" have the word "potential" in it?

In physics, potential energy is the energy held by an object because of its position relative to other objects, stresses within itself, attachments, electrical charge, magnetic field, mass, etc., and ...
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4 votes

Stress-strain Curve Interpretation

The stress-strain curve isn't created using a incremental load. Instead what most standards for tensile testing nowadays require a constant displacement rate. I.e. you have a setup similar to the ...
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4 votes

Derivation of static & kinetic friction formula

Coulomb friction is an empirical law. It was observed that the force required to move an object was proportional to its weight. Regarding static and kinetic friction it is possible to use graphs like ...
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4 votes

Why does "potential energy" have the word "potential" in it?

The block in itself has no energy. If you build a kettle of water around it, the water will not heat up. If you attach axles to it, the axles will not suddenly start spinning. However, since we spent ...
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3 votes

Is kinetic energy on a body in vacuum = 0?

No. The equation you wrote represents the change in kinetic energy due to a change in the speed of motion. Energy is required to start the motion, in a vacuum, the body stores the terminal energy with ...
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2 votes
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Do tensile and compressive forces have significance only in pairs?

If a compressive force is applied, the bar will only experience compressive forces. If a tensile force is applied, the bar will only experience tensile force. They can only occur simultaneously on the ...
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2 votes

Do tensile and compressive forces have significance only in pairs?

In engineering we have external forces and internal forces or reactions. extrnal forces don't necessarily have to comtogether. eg, you can apply tension force tangentially to a bicycle wheel and it ...
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2 votes

Automatic Tissue Dispenser

Use two drive rollers with the paper gripped between, then drive the rollers with a stepper motor or even a cam and switch to control the length. That way the diameter of the supply roller is moot.
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2 votes

Derivation of static & kinetic friction formula

I think the formulas are empirical. But saying 'empirical' raises two questions: why is $\mu_k$ smaller than $\mu_s$ why is $\mu_k$ independent of velocity You can make a loose unscientific analogy ...
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2 votes

Derivation of static & kinetic friction formula

We can do it even by our crude luggage weight scale. Put our test cube weighing say 10 kg on the surface we want to test and hook it to the scale. Pull horizontally gradually, but evenly, it won't ...
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2 votes

Why does the string having length C not have an impact on the overall system?

I can see two questions. first question Why If we either increase or decrease C , the answer to the relation will not change.? The reason is that if you place fix the rope at any point along the red ...
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2 votes

Understanding velocity of points of wheel

The relationship between the rotational speed and the linear speed is expressed as: $v = \dfrac{2\pi}{60}*r*N$ N is the rotational speed - revolution per minute. If we set N = 1, then the equation ...
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2 votes
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How to replace these two forces with one force?

As you have calculated the torque on the bar is $$\tau= (P+q)A$$ and a net force $$F=P-Q$$ This will cause the bar to turn with an angular acceleration, $$\alpha=\frac{\tau}{I}$$ and also accelerate ...
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2 votes
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How to Calculate Approximate Fuel Consumption from Engine Specs

In short, it's complicated. In long: What you tried is the cylinder volume times revolutions per minute. Indeed, this gives the per minute volume of air-fuel mix entering each cylinder of the engine. ...
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2 votes

Work done by a force in a deformable body

Work is a strange but useful mathematical concept. It is very handy because it is conservative in inertial frames. It also has an intuitive meaning most of the time, but not always. This is what gets ...
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1 vote
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Is there a way to solve this complex statics problem algebraically?

The idea was correct, and all your calculations were correct. You only neglected to consider the sign of the generating moment, i.e. in the 2D case the moments of a force are given by the following ...
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1 vote

Stress-strain Curve Interpretation

For engineering stress-strain curve, the only region where you would see basically two discrete strain values for one single value of stress is the necking, i.e. the region beyond Ultimate point on ...
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1 vote
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Energy consumed by a two-link planar manipulator with feedback control

Just some general notes. In general when one deals with dynamics problems vectors and their products can be quite a burden and a hassle. My advice is clear up the notions of cross $\times$ and dot ...
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1 vote

Energy consumed by a two-link planar manipulator with feedback control

You do not have a source of energy storage in your systems like a spring or flywheel. That would give you restoring force and you need to calculate positive and negative work. But in your case, you ...
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1 vote

How to calculate the pressure applied in a compressible fluid?

Hydrogen will not liquify no matter how high it is compressed. Unless it is cooled down to its critical temperature which is $ - 252.8^{\circ}C$ Hydrogen can be physically stored as either a gas or a ...
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1 vote

How to calculate the pressure applied in a compressible fluid?

You need to find the compressibility factor, which is defined as $Z = \dfrac{pV}{nRT}$ of the hydrogen, then correlate to the "ideal gas", which has a compressibility factor of 1. https://en....
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1 vote

Why does the string having length C not have an impact on the overall system?

Constraint Method for Pulley Problems Assumptions: The string is taut and inextensible at each and every point of time. The string is massless and hence the tension is uniform throughout. Pulley is ...
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1 vote

Why does the string having length C not have an impact on the overall system?

I am trying to read your diagram correctly but it seems to me that if $d_C$ is the differential change of C, then of course it is zero. The length of C could be 100 meters or 1 cm, as long as the ...
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1 vote

Why is the direction of static friction towards centre in case of circular turning?

When a car moves in a circular trajectory a centrifugal force is ""compelling" the car to maintain its straight line. In order for the car to move in the circular trajectory a ...
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1 vote
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Why is direction of velocity in front direction

The car steering is designed to set the alignment of the four wheels to follow the curve of rotation without any skidding. At any $\Delta t$ time the car experiences two components of force, ...
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1 vote

Why is direction of velocity in front direction

If you are implying that the drawing does not show the wheels turning its just because this is a simplification. The velocity is always tangential to the trajectory in space of the material point. ...
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1 vote

Derivation of static & kinetic friction formula

Lets talk about a material first. Assume you have Copper sheet/bar, and you conduct an experiment on it. You apply a force and track its behavior during the application of force, like deformations. ...
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1 vote

Understanding velocity of points of wheel

Try this: Figure 1. Annotated version of diagram. Point $a$ is at angle $A$ from the point of contact with the ground. It has two components to its velocity - that of the wheel's general movement, $...
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