Physics definitions

Principle of Homogeneity

Equations which are governed by laws of Physics must be homogeneous. But homogeneous equations need not necessarily obey the laws of Physics.

Scalar

A scalar is a physical quantity which has magnitude but no direction.

Vector

A vector is a physical quantity which has both magnitude and direction.

Systematic Errors

Systematic errors are errors associated with measurements that occur according to some fixed rule or pattern such that they yield a consistent over-estimation or under-estimation of the true value.

Random Errors

Random errors are errors associated with repeated measurements of different magnitude and sign such that they are scattered about the mean value.

Accuracy

Accuracy is the closeness of a measured value to the true value.

Precision

Precision is the closeness of measured values relative to one another, regardless of the true value.

Distance

Distance is the total length of the path travelled by a body.

Displacement

Displacement is the distance travelled in a straight line in a specified direction from the initial position to the final position.

Velocity

Velocity is the rate of change of displacement.

Average velocity

Average velocity is the change in displacement over the time taken.

Acceleration

Acceleration is the rate of change of velocity.

Average Acceleration

Average acceleration is the change in velocity over the time taken.

N1L

Newton's first law states that an object continues in its state of rest or continues in motion with the same velocity unless acted on by a resultant external force.

Linear momentum

The linear momentum p of an object of mass m moving with velocity v is defined as the product of its mass and velocity.

N2L

The rate of change of momentum of a body is proportional to the resultant external force acting on it and is in the direction of the resultant force.

Impulse

The impulse of a force is the product of the average force and the time interval over which it is applied.

N3L

If body A exerts a force on body B, then body B will exert an equal and opposite force on body A.

POCOM

The principle of conservation of momentum states that the total momentum of the system remains the same provided no resultant external force acts on the system.

Elastic Collision

An elastic collision is one in which the total kinetic energy of the system is conserved before and after the collision.

Inelastic collision

An inelastic collision is one in which the total kinetic energy of the system is not conserved before and after the collision.

Newton

One newton is the amount of force required to give a 1 kg mass an acceleration of 1 ms^-2.

Force Field

A force field is a region of space in which a particle experiences a force due to a physical property that it possesses.

Center of Gravity

The center of gravity of an object is the single point at which the entire weight of the object may be considered to act.

Hooke's Law

Hooke's law states that the extension or compression x of an elastic object is proportional to the applied force F, provided the limit of proportionality is not exceeded.

Moment of a force

The moment of a force about a point is the product of the force and the perpendicular distance from the line of action of the force to the point.

Torque of a couple

The torque of a couple is the product of one of the forces and the perpendicular distance between the 2 forces.

Conditions for Equilibrium

The body is in equilibrium if the net force in any direction on the body is zero and the net torque about any axis on the body is zero.

POM

Principle of moments states that for a body in rotational equilibrium, the sum of clockwise moments about any point is equal to the sum of anticlockwise moments about the same point.

Upthrust

Upthrust is the upward force exerted by a fluid on a submerged or floating object. It arises due to the difference in pressure between the upper and lower surfaces of the object.

Archimedes' Principle

Archimedes' principle states that when an object is floating or submerged in a fluid, the upthrust on the object is equal in magnitude and opposite in direction to the weight of fluid displaced by the object.

Principle of floatation

Principle of floatation states that when an object floats in equilibrium, the upthrust acting on the object is equal in magnitude and opposite in direction to the weight of the object.

Work done

The work done by a constant force on a body is defined as the product of the force and the displacement in the direction of the force.

KE

Kinetic energy is the energy of a body due to its motion.

GPE (WEP)

Gravitational potential energy is the energy stored in a mass due to its position in a gravitational field.

Elastic PE

Elastic potential energy is the energy stored in a body due to extension, compression or change of shape.

Electric PE (WEP)

Electric potential energy is the energy stored due to the position of a charge in an electric field.

POCOE

Energy can neither be destroyed nor created in any process. It can be transformed from one form to another, and transferred from one body to another, but the total amount remains constant.

Power

Power is defined as the rate at which work is done.

Angular displacement

Angular displacement θ is defined as the angle an object makes with respect to a reference line.

Radian

One radian is defined as the angle subtended at the centre of a circle by an arc equal in length to the radius of a circle.

Angular velocity

Angular velocity ω is defined as the rate of change of angular displacement.

Newton’s law of gravitation

Newton’s law of gravitation states that 2 point masses attract each other with a force that is proportional to the product of their masses and inversely proportional to the square of the separation between them. Assuming masses are point masses such that their separation is much larger than their radii.

Gravitational field

A gravitational field is a region of space in which a mass experiences a force due to the presence of another mass.