Strenuous activities demand more energy because they involve increased muscle work, higher metabolic rates, and greater expenditure of stored energy reserves to sustain prolonged physical effort.

These activities are fueled by the energy obtained from food through metabolic processes like respiration, which convert stored energy into usable forms for muscle movement and other bodily functions.

The energy for life processes comes from food, which is broken down through digestion and utilized by cells through processes like respiration.

Living beings need to perform life processes such as respiration, digestion, circulation, and excretion to survive.

The gravitational force experienced by an object near the Earth’s surface increases with decreasing distance between the object and the Earth’s center, which is typically represented by the radius of the Earth, denoted as ‘R’.