The 60 kg skateboarder coasts down a circular track. if he starts from rest when , determine the magnitude of the normal reaction the track exerts on him when . neglect his size for the calculation

The freezing and boiling point of a substance changes as the air pressure around it changes. for example, at a lower air pressure (higher altitude) it is easier for water molecules to escape from liquid into the air. in a high altitude city such as denver, colorado compared to a sea-level city such as houston, texas, water