Question

While standing stationary and writing on a patient's chart, a doctor drops her pen. What can we say about the pen's motion after she drops it? Ignore air resistance

Answer 1

Here since we are ignoring the air resistance and considering the height not to be very high as well (doctors hand) the motion of the pen will be that of a body under free fall. That is the pen would fall in a straight line in the downwards direction under the influence of gravity and would continue to move with increasing velocity until it hits the ground. This will be a case of projectile motion in one dimension. (yes,projectile motion is not only limited to two dimensions. This is just one special case of projectile motine in one dimension).

Furthermore as the pen continue to fall its potential energy would turn into kinetic energy as it reaches the ground.