Question: Unit Exam - Energy and Work
The object at point A has a potential energy of 300 J and a total energy of 400 J. What is the kinetic energy?
1. **State the problem:**
We are given the potential energy ($$PE$$) and total energy ($$E_{total}$$) of an object at point A, and we need to find its kinetic energy ($$KE$$).
2. **Recall the formula:**
The total mechanical energy of an object is the sum of its potential energy and kinetic energy:
$$E_{total} = PE + KE$$
3. **Rearrange the formula to solve for kinetic energy:**
$$KE = E_{total} - PE$$
4. **Substitute the given values:**
$$KE = 400 - 300$$
5. **Calculate the kinetic energy:**
$$KE = 100$$
6. **Interpretation:**
The kinetic energy of the object at point A is 100 J.
**Final answer:**
$$KE = 100\text{ J}$$