Unit 4 WORK , POWER & ENERGY THEORY NOTES

What is work in physics?

Work is an act to transfer energy from one body to another.

What is the formula for work done when a force displaces a body?

W = F * S, where W is work, F is force, and S is distance.

Is work a scalar or vector quantity?

Work done is a scalar quantity.

What are the two systems of units for measuring work?

1. Absolute system of units 2) Gravitational system of units.

How many joules are in one erg?

One joule is equivalent to 10^7 ergs.

What is the formula for gravitational potential energy?

Gravitational potential energy is defined as U = mgh, where m is mass, g is acceleration due to gravity, and h is height.

What is the relationship between power and work?

Power is defined as the rate of doing work, expressed as P = W / t.

What type of energy is associated with an object in motion?

Kinetic energy is the energy possessed by a body by virtue of its motion.

What theorem relates work done to change in kinetic energy?

The Work-Energy Theorem states that work done by the force in displacing a body is equal to the change in its kinetic energy.

What is the principle of conservation of mechanical energy?

The total mechanical energy (sum of kinetic and potential energy) remains constant for conservative forces acting on a system.

What is the formula for the elastic potential energy stored in a spring?

The potential energy stored in a spring is given by P.E. = (1/2) Kx², where K is the spring constant and x is the displacement.

Define conservative forces.

Conservative forces are forces for which the work done depends only on the initial and final positions, not on the path taken.

Provide an example of a non-conservative force.

Frictional forces are an example of non-conservative forces as they depend on the path followed.

What is the SI unit of power?

The SI unit of power is the watt (W), equivalent to one joule per second.

What does the force constant (K) of a spring depend on?

The force constant depends on the length of the spring, the radius of the spring, and the nature of the material of the spring.

What is the relationship between kinetic energy (KE) and momentum (p)?

K.E. = p² / (2m), where p is momentum and m is mass.

What does mass-energy equivalence imply?

Mass-energy equivalence implies that mass can be converted into energy and vice versa, as described by E = mc².