Explain the potential energy and kinetic energy involve when we through a ball from a certain height
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When we hold a ball at a certain height, it possesses potential energy due to its position above the ground. The potential energy equals mass times gravity times height. Initially, if the ball is at rest, its kinetic energy is zero since it has no velocity.
When the ball is released and begins to fall, energy transformation occurs. As the ball loses height, its potential energy decreases. Simultaneously, gravity accelerates the ball downward, increasing its velocity and kinetic energy. The green arrow shows the increasing velocity as the ball falls.
The principle of conservation of energy states that the total mechanical energy remains constant during the fall. This graph shows how potential energy decreases while kinetic energy increases by exactly the same amount. The green line represents the constant total energy, demonstrating that energy is neither created nor destroyed, only transformed from one form to another.
At the highest point of the ball's trajectory, potential energy reaches its maximum value of mgh, while kinetic energy is zero since the ball momentarily stops. Just before impact with the ground, the situation reverses: potential energy becomes zero while kinetic energy reaches its maximum value, also equal to mgh. This demonstrates the complete conversion between the two forms of energy while maintaining constant total energy.
In the real world, air resistance plays a significant role in the ball's motion. As the ball falls through air, it experiences drag force that opposes its motion. This resistance converts some of the mechanical energy into heat and sound, causing the total mechanical energy to decrease. Consequently, the ball reaches the ground with less kinetic energy and lower speed than predicted by the ideal conservation of energy model. This demonstrates why real-world applications must account for energy losses due to friction and air resistance.