The lower surface of a cube is fixed. On its upper surface, force is applied at an angle of `30^@` from its surface. The change will be the type

Options

A. shape
B. size
C. volume
D. Both shape and size

Explanation

To solve the problem, let's analyze the situation step by step.

### Step 1: Understand the Setup
We have a cube with its lower surface fixed. A force is applied at an angle of 30 degrees to the upper surface. The fixed lower surface means that the cube cannot move vertically downwards.

**Hint:** Visualize the cube and the direction of the applied force to understand how it affects the cube.

### Step 2: Identify the Types of Strain
When a force is applied to an object, it can cause different types of deformation. In this case, we need to consider:
- **Longitudinal Strain:** This occurs when the force is applied in the direction of the length of the object.
- **Shear Strain:** This occurs when the force is applied parallel to the surface, causing a change in shape.

**Hint:** Recall the definitions of longitudinal and shear strain to differentiate between the two.

### Step 3: Analyze the Force Application
Since the force is applied at an angle of 30 degrees, we can break it down into two components:
- A vertical component that may cause longitudinal strain.
- A horizontal component that will cause shear strain.

**Hint:** Use trigonometric functions (sine and cosine) to resolve the force into its components.

### Step 4: Determine the Resulting Deformation
Due to the fixed lower surface, the cube will experience both:
- **Longitudinal deformation** due to the vertical component of the force.
- **Shear deformation** due to the horizontal component of the force.

This means that both the shape and size of the cube will change.

**Hint:** Think about how the fixed surface affects the overall deformation of the cube.

### Step 5: Conclusion
The application of the force at an angle of 30 degrees results in both longitudinal and shear strains, leading to a change in both shape and size of the cube.

**Final Answer:** The change will be of both shape and size due to the combined effects of longitudinal and shear strains.

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