Question

You drop your textbook off the roof of a building, where it passes identical windows on the second and first floors of the building. Which window will it pass more quickly, and why? Is the increase in speed of the book as it drops past the second floor window the same, less than, or greater than the increase in the speed of the book as it drops past the first floor window? Why?

Answer 1

When the book is thrown downwards, it is acted upon by gravity which produces a constant acceleration of about 10 m/s on the book.

Due to acceleration downwards, which is in same direction of motion of the book, the velocity will increase as the book moves downwards. So at second floor its velocity is less than at first floor and hence it will take less time to pass the window at first floor.

As acceleration throughout the motion is constant, so the change in the velocity is always constant as acceleration brings about change in velocity. So increase in the speed of the book is same always.