Krish fell down while playing and his knee got injured. Blood was coming out from the cut. After some time, he noticed that bleeding had stopped and a dark red clot had plugged the cut. Krish was amazed to see this. Name the type of cells responsible for the formation of this clot.

While learning to ride a bicycle Boojho lost his balance and fell. He got bruises on his knees and it started bleeding. However, the bleeding stopped after some time
(a) Why did the bleeding stop?
(b) What would be the colour of the wounded area and why?
(c) Which type of blood cells are responsible for clotting of blood?

Appu’s injury stopped bleeding within minutes and a black scab was beginning to form. “Ewww...” exclaimed Appu, though he was relieved to see the bleeding stop. The doctor further explained that “Blood forms a clot to begin the process of healing. Some components block the leakage of blood and close the body from the outside world. This is the clot and the process of rebuilding the skin starts as soon as it is formed.”

Which component of blood is the doctor referring to?

While playing a football match, Krish collided and got entangled with Tom who was playing for opposite team and running from opposite side. The mass of Krish was 40 kg and the mass of Tom was 60 kg. If Tom was running with a velocity of 4 m/s and Krish was running with a velocity of 3 m/s, If Krish stops completely, find the velocity of tom after collision assuming other forces were negligible (in m/s).