When work done by force of gravity is negative, then

Options

A. PE increases
B. KE increases
C. PE remains constant
D. PE decrease

Explanation

To solve the question "When work done by force of gravity is negative, then what happens to potential energy and kinetic energy?", we can follow these steps:

### Step 1: Understand the Concept of Work Done by Gravity
The work done by a force is defined as the product of the force and the displacement in the direction of the force. For gravity, the force acts downward. If an object moves upward against the force of gravity, the work done by gravity is negative because the displacement is in the opposite direction to the gravitational force.

**Hint:** Remember that work can be positive, negative, or zero depending on the direction of the force and displacement.

### Step 2: Analyze the Movement of the Object
When an object moves upward, it is moving against the force of gravity. This means that the height of the object is increasing. As the height increases, the potential energy of the object also increases. The formula for gravitational potential energy (U) is given by:
\[ U = mgh \]
where \( m \) is the mass, \( g \) is the acceleration due to gravity, and \( h \) is the height.

**Hint:** Think about how potential energy is related to height in a gravitational field.

### Step 3: Consider the Kinetic Energy
Kinetic energy (K.E.) is given by the formula:
\[ K.E. = \frac{1}{2} mv^2 \]
where \( v \) is the velocity of the object. The work done on the object can change its kinetic energy. If the object is moving upward slowly, it can be in a state where the net force is zero (the applied force equals the weight of the object). In this case, the kinetic energy can remain constant (zero change).

**Hint:** Kinetic energy can vary based on the net forces acting on the object and its velocity.

### Step 4: Conclusion
When the work done by gravity is negative (object moving upward), the potential energy of the object increases. The kinetic energy can be constant, increasing, or decreasing depending on the net forces acting on the object. Thus, we cannot determine a specific change in kinetic energy without additional information.

**Final Answer:** The potential energy increases, and the kinetic energy can be anything (positive, negative, or zero).