Q: An air mattress is filled with air to a pressure greater than the atmospheric pressure . When will the air pressure in the mattress be greater . when a man stands on it or when he lies on it ?
Sol: If the man stands on the mattress , his weight will be distributed over a small area , that is the area of his feet than when he lies down . Hence , the air pressure in the mattress will be greater when the man stands than when he lies on it .