Choose the correct option for each question. There is only one correct response for each question.
A force of 20N is applied on an object. The object remains stationary. What is the magnitude of static friction?

Options

A. 0N
B. 10N
C. 20N
D. 40N

Answer

To solve the problem, we need to determine the magnitude of static friction acting on the object when a force of 20 N is applied, and the object remains stationary.

### Step-by-Step Solution:

1. **Understand the Situation**:
- A force of 20 N is applied to an object.
- The object does not move, meaning it is stationary.

2. **Identify the Forces**:
- The applied force (F_applied) is 20 N in one direction.
- There is a force of static friction (F_friction) acting in the opposite direction to keep the object stationary.

3. **Apply Newton's First Law**:
- According to Newton's First Law, if an object is at rest, the net force acting on it must be zero (F_net = 0).

4. **Set Up the Equation**:
- Since the object is stationary, we can express the net force as:
\[ F_{net} = F_{applied} + F_{friction} = 0 \]
- Plugging in the values, we have:
\[ 20 N + F_{friction} = 0 \]

5. **Solve for Static Friction**:
- Rearranging the equation gives:
\[ F_{friction} = -20 N \]
- The negative sign indicates that the direction of the static friction force is opposite to that of the applied force.

6. **Determine the Magnitude**:
- The magnitude of static friction is the absolute value of the force:
\[ |F_{friction}| = 20 N \]

7. **Conclusion**:
- The magnitude of static friction acting on the object is 20 N.

### Final Answer:
The magnitude of static friction is **20 N**.

---