A ball is dropped from a building onto a scale below. The ball has a mass of 2.1 kg and the scale reads 20.5 N at the moment of impact. What is the gravitational acceleration constant, the rate of acceleration for an object in free fall, for planet Earth?

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Quizplus · Accepted Answer

The formula to find the required force is force = mass in kg × acceleration in m/s² F=ma To find the acceleration of an object we must isolate acceleration. To do this, we divide both sides by the mass F/m = ma/m F/m = a Then we plug in the numbers from the problem. 20.5 N / 2.1 kg = 9.76 m/s2 which rounds up to 9.8 m/s2 *The gravitational acceleration constant for the earth is -9.8 m/s². The negative sign is because gravity is toward the center of Earth, down, and this is typically regarded as the negative direction. This is the rate at which any object in freefall accelerates. This is NOT dependant on the mass of the object. A feather and a large rock will fall with the same speed in a vacuum, which is a space where there is no air. The force at which they experience is different because of their mass. Usually, these objects do not fall in a vacuum and thus experience drag forces which slow the feather down more than the rock.

A Ball Is Dropped from a Building onto a Scale