An elevator ascends from the ground with uniform speed. a time tį later, a boy drops a marble through a hole in the floor. a time t2 after that (i. e. ti +t2 after start) the marble hits the ground. find an expression for the height of the elevator at time ti. (local gravity is g.) what checks can you make?

Explanation:

Let Ye be the position of the elevator, Ve be the velocity of the elevator and Ym the position of the marble. We know that:

  Since the marble hits the ground at T2, Ym=0m

Replacing Ye into the equation for Ym:

  Solving for Ve:

 Replcaing this value into Ye:

If we check units of Ye expression, they must be distance units.

explanation:

as the height from which the ruler was dropped increased, the speed of the ruler at ryan's hand increased.

the minimum amperage that the current in this wire would have to have so that its weight is completely supported by the magnetic force due to earth's field, assuming that no other forces except gravity act on it