Friction is considered a necessary evil. We cannot do anything without the force of friction. If there was no friction, the motion of a body would not cease at all and continue perpetually. Friction has made it possible to write on paper with a pencil or a pen. We can walk as there is friction … Read more
Why cooking at the top of hill is difficult? At higher altitudes, like hills, cooking food is difficult. Higher altitudes mean lower atmospheric pressure. The boiling point decreases if the pressure is low. So, at the top of the hill cooking takes a long time because due to lower pressure water starts to boil at … Read more
We know, velocity is a vector. It has both value and direction. So, change in direction or value will result in change of vector. So, if direction of an object going at uniform velocity changes, velocity will also change. Meaning, uniform speed does not always mean uniform velocity.
Specific heat is the quantity of heat required to raise the temperature of 1gm of a substance by 1 degree. The human body is composed of water, protein fat, and minerals. Its specific heat reflects this composition. With 75% water and 25% protein, the specific heat of the body would be Specific heat = 0.75 … Read more
Ultraviolet light produces reactions in the skin then visible light. Some of these reactions are beneficial and some are harmful. One of the major beneficial effects of UV light from the sun is the conversion of molecular products in the skin into vitamin D. Ultraviolet light from the sun affects the melanin in the skin … Read more
The walls of the heart consist of layers of muscle, wound several times around the atria and the ventricles in a complicated arrangement. The layers of muscle around the ventricles are thicker than those around the atria. The heart muscle pumps blood by its cyclic contractions and relaxation. The contracted phase of the heart is … Read more
Each of the pumps in the heart has two chambers. The upper chamber is called the atrium, and the lower chambers the ventricle (“belly”). The atria accumulate the blood arriving at the heart and then inject it into the ventricles. The ventricles eject the blood from the heart into the arteries; they perform most of … Read more