Question

what is the relation between weight of the body and it's number of heart beat

Answer 1

With more body size and increased body weight the heart rate also increase. Heart rte is referred as the time of beating of heart in each minute. A healthy person could have 60-80 bpm and a person with more weight need a heart to pump blood with greater efficiency so heart beat can be around 100 or greater 

Answer 2

The heart is essentially a pump, designed to circulate blood throughout the body. Many things can interfere with the heart's ability to pump efficiently, which includes excess unhealthy body weight. A normal adult's  heart beats between 60 and 90 times per minute. An athlete's heart beats between 40 and 60 times per minute.

The number of times the heart beats per minute is called the heart rate. It increases and decreases depending on the amount of demand placed on the muscles. When the demand is high, the heart has to pump harder to deliver extra oxygen to the muscles for metabolism. Extra fat increases the workload of the muscles and causes an increase in heart rate. The total body weight does not count so much, it is the ratio of fat to lean mass, known as the body composition which makes the difference.