Choose the correct option for each question. There is only one correct response for each question.
Which object will be most difficult to move?

Options

A. An object of mass 10kg
B. An object of mass 15kg
C. An object of mass 20kg
D. An object of mass 25kg

Answer

To determine which object will be the most difficult to move based on the given masses, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Friction**: Friction is the force that opposes the motion of an object. It is directly proportional to the normal force acting on the object. The normal force (N) is equal to the weight of the object when it is resting on a horizontal surface.

2. **Identify the Masses**: We are given four objects with different masses:
- Object 1: 10 g
- Object 2: 15 g
- Object 3: 20 g
- Object 4: 25 g

3. **Calculate the Normal Force**: The normal force can be calculated using the formula:
\[ N = m \cdot g \]
where \( m \) is the mass of the object and \( g \) is the acceleration due to gravity (approximately \( 9.8 \, \text{m/s}^2 \), but for simplicity, we can use \( 10 \, \text{m/s}^2 \)).

4. **Calculate Normal Forces for Each Object**:
- For Object 1 (10 g):
\[ N_1 = 10 \, \text{g} \times 10 \, \text{m/s}^2 = 100 \, \text{N} \]
- For Object 2 (15 g):
\[ N_2 = 15 \, \text{g} \times 10 \, \text{m/s}^2 = 150 \, \text{N} \]
- For Object 3 (20 g):
\[ N_3 = 20 \, \text{g} \times 10 \, \text{m/s}^2 = 200 \, \text{N} \]
- For Object 4 (25 g):
\[ N_4 = 25 \, \text{g} \times 10 \, \text{m/s}^2 = 250 \, \text{N} \]

5. **Compare the Normal Forces**: Now that we have calculated the normal forces:
- \( N_1 = 100 \, \text{N} \)
- \( N_2 = 150 \, \text{N} \)
- \( N_3 = 200 \, \text{N} \)
- \( N_4 = 250 \, \text{N} \)

6. **Determine the Most Difficult Object to Move**: Since friction is directly proportional to the normal force, the object with the greatest normal force will have the greatest friction and will therefore be the most difficult to move. Here, \( N_4 \) is the greatest.

7. **Conclusion**: The object with a mass of 25 g will be the most difficult to move.

### Final Answer:
The object of mass 25 g will be the most difficult to move.