### Elastics, Plastics and Hooke's Law

Some materials increase in size when stretched, decrease in size when compressed, and snap back to their original shape when the deforming force is withdrawn. Such materials are said to be elastic. If the force exceeds some threshold value however, the materials do not regain their original shape after the deforming force is withdrawn. The point at which this occurs is referred to as the elastic limit (elastic limit is defined as the point beyond which an elastic material does not regain its shape after the deforming force is withdrawn). Examples of elastic materials are rubber, steel, and coils (springs). ...read more.

### Equilibrium, Moment of force, Work and Machines

Center of gravity (cog) is the point on a body where the entire weight of the body acts. The lower the center of gravity, the more stable an object is. This means that it is more difficult to topple a stable object compared to an unstable one. One way of lowering the center of gravity of an object is by making the base relatively heavy.  Buses for example are constructed with luggage cabins on the lower sections, with limited load (carry-on luggage) being allowed in. ...read more.

### Temperature, Heat Transfer, Calorimetry

Temperature is the degree of hotness or coldness of an object. It is measured using a thermometer. A thermometer employs a substance with a property referred to as a thermometric property that varies with temperature. ...read more.

### Gas Laws and the Kinetic Theory of Gases

When an inflated balloon is left out in the sun, it increases in volume without extra air being pumped in. If the balloon is taken out of the sun and placed in a cold room, the volume reduces without any air escaping. Out in the sun, the temperature of air in the balloon rises and the gas expands leading to an increase in volume. In the cold room, the temperature of the air in the balloon reduces and consequently the air contracts hence volume reduces. This implies that when temperature of air (gas) increases, the volume of the gas increases and vice versa. For this to happen, the pressure and mass of the gas must be kept constant. Hence;...read more.

### Circular Motion

Circular motion refers to motion along a curved path e.g., a roundabout. Suppose an object moving along a circular path of radius r covers a distance represented by the arclength AB (a section of the circumference of a circular path of a circle is referred to as arclength), sweeping an angle  about the center O....read more.

### Upthrust, Viscosity and Terminal Velocity

Objects float if they are less dense than, or of equal density with, the fluids (liquids and gases) they occupy. For example, while steel is denser than water, a steel ship can be made to float by introducing air-filled chambers which reduce the density of the ship relative to that of water. Floating bodies usually have part (or all) of their bodies in the liquid and as a result experience an upward force called upthrust (or buoyant force). Consider for instance an object of mass m, cross-sectional area and height fully submerged in a liquid of density ρ....read more.

### Pressure, Continuity and Bernoulli's principles

Pressure refers to the force a body exerts perpendicularly per unit surface area i.e....read more.

### Linear Motion, Newton's Laws, Friction

When an object moves along a line, it is said to undergo linear motion. If it moves along a circular path or a bend, it is said to undergo circular or rotational motion. If the object moves to-and-fro about a mean position, it is said to undergo vibratory or oscillatory motion. ...read more.