holt science spectrum physical science with earth and space science

Structure of Atom - When scientists started exploring matter, they discovered that the smallest particle of an element that maintains its chemical identity through all chemical and physical changes is called and 'atom'. Just how small these atoms are can be made out if you realize that th..

Structure of the earth system Earth's history Earth in the solar syste..

Structure of the earth system Earth's history Earth in the solar syste..

Properties of earth materials Objects in the sky Changes in earth and sk..

01. The Earth's gravitational force causes an acceleration of 5 m/s 2 in a 1 kg mass somewhere in space. How much will the acceleration of a 3 kg mass be at the same pla..

The addition of certain pollutants like the carbon dioxide gases increases the temperature of the earth. These gases remain close to the surface of earth, forming an insulating layer. The surface becomes hot due to the solar radiations. This radiation is normally reflected back..

We often hear that an astronaut experiences weightlessness in space. What does this mean? Let us perform a simple experiment to demonstrate weightlessness. Suspend a stone from a spring balance, the pointer of the spring balance shows the weight of the stone. Allow the spring balance alon..

Solar energy is responsible for the blowing of wind. The intensity of sun-rays is stronger near the Equator than at the Polar Regions. Due to unequal heating of the earth's surface, cooler air from the Polar Regions flow towards the equatorial regions to fill the space created..

. These developments indicate a gradual change in the life style of mankind. Today metals are so vital to the modern man that it is unthinkable to live without them. They are essential for the construction of houses, transportation, communication, electricity, household articles, scientific instrum..

Around (600 - 500 B.C) the 'Samkhya' philosophy was popular. It asserted that matter was made up of five 'bhutas' or elements consisting of akasa (sky or space), vayu (air), tejas (fire), ap (water) and kshiti (the Earth). These bhutas, besides sharing common properties like co..