Question

A 72.0-kg object hits the ground at a velocity of 79.0 m/s. Neglecting air resistance, which relationship allows you to calculate the object’s potential energy before the fall? A. PE = mgh B. (PE)beginning = (KE)end C. Mechanical Energy = PE + KE D. KE = 1/2 mv2

Answer 1

B. (PE)beginning = (KE)end

Step-by-step explanation:

We are given;

• Mass of an object is 72.0 kg
• Velocity of the body before it hits the ground is 79.0 m/s

We are required to determine the relationship between the potential energy and kinetic energy before the fall.

• When an object is at the highest point, it has maximum potential energy and minimum kinetic energy.
• This is because potential energy is directly proportional to the height of an object above the earth's surface.
• On the other hand, when an object attains the highest speed it has maximum kinetic energy and minimum kinetic energy.

In this case;

• The velocity of the object when hitting the ground is maximum and thus the object will have maxim,um kinetic energy.
• As the object falls towards the ground the potential energy is being converted to kinetic energy.
• Therefore, the potential energy at the beginning will be equal to the kinetic energy at the end when the object is on the ground.
• We can therefore, conclude that, (PE)beginning = (KE)end