A 5 kg object is dropped from a height of 20 m. What is the total mechanical ene

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Question: A 5 kg object is dropped from a height of 20 m. What is the total mechanical energy just before it hits the ground?

Options:

Correct Answer: 200 J

Solution:

Total mechanical energy is conserved. At height, PE = mgh = 5 * 9.8 * 20 = 980 J. Just before hitting the ground, total energy = 980 J.

A 5 kg object is dropped from a height of 20 m. What is the total mechanical energy just before it hits the ground?

A 5 kg object is dropped from a height of 20 m. What is the total mechanical energy just before it hits the ground?

Step 1: Identify the mass of the object. In this case, the mass (m) is 5 kg.
Step 2: Identify the height from which the object is dropped. The height (h) is 20 m.
Step 3: Use the formula for gravitational potential energy (PE), which is PE = mgh.
Step 4: Substitute the values into the formula: PE = 5 kg * 9.8 m/s² * 20 m.
Step 5: Calculate the potential energy: PE = 5 * 9.8 * 20 = 980 J.
Step 6: Understand that total mechanical energy is conserved, meaning it remains the same throughout the fall.
Step 7: Conclude that just before the object hits the ground, the total mechanical energy is still 980 J.

Potential Energy (PE) – The energy an object possesses due to its position in a gravitational field, calculated as PE = mgh.
Conservation of Mechanical Energy – The principle stating that the total mechanical energy (potential + kinetic) in a closed system remains constant if only conservative forces are acting.