A ball has a potential energy of 180 J and a kinetic energy of 0 J. After falling 2m, it has a potential energy of 135J. What is its kinetic energy at this point?
To find the kinetic energy of the ball at a given point, we can use the principle of conservation of energy. According to this principle, the total mechanical energy of an object remains constant as long as no external forces are acting upon it.
The total mechanical energy of an object is the sum of its potential energy and kinetic energy. So, if we know the potential energy at one point and want to find the kinetic energy at another point, we can subtract the potential energy change from the initial potential energy to find the final potential energy. Then, we can subtract the final potential energy from the total mechanical energy to find the kinetic energy.
Let's break down the given information:
Initial potential energy = 180 J
Kinetic energy = 0 J
Potential energy at another point = 135 J
Final kinetic energy = ?
Since the initial kinetic energy is given as zero, we can consider the initial potential energy as the total mechanical energy.
Total mechanical energy at the initial point = Initial potential energy = 180 J
Now, we need to find the final potential energy by subtracting the potential energy change from the initial potential energy:
Potential energy change = Initial potential energy - Potential energy at another point
Potential energy change = 180 J - 135 J = 45 J
The final potential energy is given as 135 J.
Now, we can find the final kinetic energy:
Final kinetic energy = Total mechanical energy at the final point - Final potential energy
Final kinetic energy = Initial potential energy - Potential energy change - Final potential energy
Final kinetic energy = 180 J - 45 J - 135 J
Final kinetic energy = 0 J
Therefore, the kinetic energy of the ball at the given point is 0 J.