An elevator descends from the top of a building and stops at the ground floor, what becomes of the energy that had been potential energy or the work of gravity?

The angle of elevation of the top of a tower from the bottom of a building is twice that from its top. What is the height of the building, if the height of the tower is 75 m and the angle of elevation of the top of the tower from the bottom of the building is 60^@ ?

The angle of elevation of the top of a tower from the bottom of a building is twice that from its top. What is the height of the building if the height of the tower is 75 m and the angle of elevation of the top of the tower from the bottom of the building is 60^(@) ?

In the Suniti building in Mumbai there are 12 floors plus the ground floor. 9 people get into the lift of the building on the ground floor. The lift does not stop on the first floor. If 2, 3 and 4 people alight from the lift on its upward journey, then in how many ways can they do so? (Assume they alight on different floors.)

The angle of elevation of the top of a building and the top of the chimney on the roof of the building from a point on the ground are x and 45^(@) respectively .The height of building is h metre .Then the height of the chimney (in metre ) is :

50 J of work is done against the force of gravity in lifting a stone to a certain height. What will be the potential energy of the stone at that height ?

20 J of work is done against the force of gravity in lifting a stone to a certain height. What will be the potential energy of the stone at that height ?

From a point A on the ground , the angles of elevation of the top of a 10 m tall building and a helicopter hovering at some height of the building are 30^(@) and 60^(@) respectively. Find the height of the helicopter above the building

The ground state energy of hydrogen atom is -13.6 eV . What is the potential energy of the electron in this state