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.

A. Its velocity is constant. B. The magnitude of its velocity is decreasing. C. The magnitude of its acceleration is increasing. D. Its acceleration is constant

Answer 1

First think why the pen is falling! The answer is gravity. The acceleration due to Earth's gravitational field is almost constant near about the Earth's surface and has value of 9.81m/s²(approx) and acting towards the center of the Earth, though the acceleration due to gravity falls off with increase in height from the earth's surface, but that fact is conciderable for relatively large heights(compared to Earth's radius) and near about Earth's surface it is constant & so option C is wrong. Since the pen has downward acceleration so the magnitude of it's velocity should increase with time so option A and option B are wrong. So the right option is D. it's acceleration is constant