Dymanics, Energy,Deformation of solids

What is the definition of work in physics?

Work is the product of the force and the displacement moved by the point of application of the force in the direction of the force.

When is work done considered positive?

When a force moves its point of application in the direction of the force, work is positive and said to be *done by the force

When is work done considered negative?

When the direction of movement is opposite the direction of the force, work is negative and said to be *done on the force.

How is work calculated when force and displacement are not in the same direction?

The component of the force in the direction of displacement must be used: Work = FdcosƟ

What is the SI unit of energy?

The joule (J), defined as the energy required to exert a force of 1 Newton through a distance of 1 meter

State the law of conservation of energy.

"Energy can neither be created nor destroyed but can only be converted from one form to another."

What is potential energy?

The ability to do work as a result of an object's position or shape (e.g., gravitational or elastic potential energy).

What is Newton's First Law of Motion?

Every body continues in its state of rest or uniform motion with constant velocity unless acted on by a resultant force.

What is Newton's Third Law of Motion?

When one body exerts a force on another, the second body exerts an equal but opposite force on the first.

Restate Newton's Third Law in terms of momentum.

The rate of change of momentum of one body due to an action force is equal and opposite to the rate of change of momentum due to the reaction force of the other body.

State the principle of conservation of momentum.

The total momentum of an isolated system remains constant, provided no external forces act on it.

What is deformation in physics?

The change in shape or size of an object due to an applied force.

What does the straight portion (O to P)of an extension-load graph represent?

Extension is directly proportional to the applied load (Hooke’s Law region).

What is the difference between elastic and inelasticobjects?

Elastic: Returns to original shape after force is removed (e.g., rubber ball).

- Inelastic: Does not regain shape after force is removed (e.g., 8 ball).

What is the proportionality limit (Point P)?

The maximum load beyond which extension is no longer proportional to the load.

What is the **elastic limit (Point E)**?

The maximum load before the object undergoes **permanent deformation (does not return to original shape).

What happens **beyond the elastic limit**?

The object undergoes plastic deformation(permanent change in shape).

What is strain energy?

The energy stored in an object when it is stretched or compressed (elastic potential energy).

How is strain energy represented on an extension-load graph?

* By the area under the graph(work done to deform the object).

What is the elastic potential energy formula for a spring?

½kx²