Find the student’s gravitational potential energy if the cliff is 80m high

P.E = 784m  joules

Explanation:

The gravitational potential energy of a body is defined as the product of the mass, acceleration due to gravity and the vertical height from the surface of Earth. It is given by the relation

                          P.E  = mgh joules

where  

                        m - mass of the body

                         g - acceleration due to gravity (9.8 m/s)

                         h - height from the surface

When a body is lifted from ground to a certain height, the work done on the body against gravitational attractive force is stored as the potential energy. When the body is released its potential energy is compensated as the kinetic energy. On hitting the ground this energy is released in the impact.

When a student of mass 'm' is at a height 80 m on the cliff, then his P.E is given by

                                P.E = m x 9.8 x 80

                                       = 754m joules   (where m is mass of student)

So, the gravitational potential energy of the student P.E = 754m J

in simple terms, the principle states that the buoyancy force on an object is equal to the weight of the fluid displaced by the object, or the density of the fluid multiplied by the submerged volume times the gravitational acceleration, g. this is also known as upthrust.

i think the answer is a, hope this is right, that would be my best guess.