True or false blood gets oxygen and releases carbon dioxide in the heart

Astone dropped into a well is heard to strike the water after 8seconds. find the depth of the well if the velocity of sound is 350m/s

Abucket full of water weights 4 kg and water well is 10m deep. a girl draws water from the well. it takes the girl 3 minutes to draw a bucket full of water from the well. what is the power of the girl?

Mechanical energy is when the amount of kinetic and potential energies added together remains the same. conserved created lost