When a satellite is lifted from a lower orbit to a higher orbit
a) Gravitational potential energy increases
b) KE decreses
c) Gravitational PE decreases
d) KE increases

Options

A. a is only correct
B. a & d are correct
C. a and c are correct
D. a & b are correct

Answer

To solve the question, we need to analyze the changes in gravitational potential energy (GPE) and kinetic energy (KE) when a satellite is lifted from a lower orbit to a higher orbit.

### Step-by-Step Solution:

1. **Understanding Orbital Mechanics**:
- A satellite in orbit around a planet experiences gravitational force, which provides the necessary centripetal force for its circular motion.

2. **Orbital Velocity**:
- The orbital velocity \( v \) of a satellite is given by the formula:
\[ v = \sqrt{\frac{GM}{r}} \]
where \( G \) is the gravitational constant, \( M \) is the mass of the planet, and \( r \) is the distance from the center of the planet to the satellite.

3. **Lifting the Satellite**:
- When a satellite is lifted from a lower orbit (radius \( r_1 \)) to a higher orbit (radius \( r_2 \)), the distance \( r \) from the center of the planet increases.

4. **Effect on Kinetic Energy**:
- The kinetic energy (KE) of the satellite is given by:
\[ KE = \frac{1}{2} mv^2 \]
- Since \( r \) increases, the orbital velocity \( v \) decreases (because \( v \) is inversely proportional to the square root of \( r \)). Therefore, as \( v \) decreases, \( KE \) also decreases.

5. **Effect on Gravitational Potential Energy**:
- The gravitational potential energy (GPE) of the satellite is given by:
\[ GPE = -\frac{GMm}{r} \]
- As the satellite is lifted to a higher orbit, \( r \) increases. Since the GPE is negative, an increase in \( r \) (the denominator) results in a decrease in the absolute value of GPE, which means GPE becomes less negative. Thus, GPE increases.

6. **Conclusion**:
- From the analysis:
- Gravitational potential energy (GPE) increases.
- Kinetic energy (KE) decreases.
- Therefore, the correct answers are:
- a) Gravitational potential energy increases
- b) Kinetic energy decreases

### Final Answer:
- The correct options are:
- a) Gravitational potential energy increases
- b) Kinetic energy decreases