To find the volume of wood in the pen stand, we first calculate the volume of the cuboid and then subtract the volumes of the four conical depressions.
The volume of the cuboid (the pen stand without the depressions) is given by length × width × height. So, it’s 15cm × 10cm × 3.5cm.
Each conical depression has a radius of 0.5 cm and a depth (height) of 1.4 cm. The volume of a cone is (1/3)πr²h. Therefore, the volume of one depression is (1/3)π × 0.5² × 1.4.
Since there are four such depressions, we multiply this volume by 4 and subtract it from the volume of the cuboid to get the volume of wood in the pen stand. This calculation gives us the amount of wood used in making the pen stand, accounting for the space occupied by the conical depressions.

A pen stand made of wood is in the shape of a cuboid with four conical depressions to hold pens. The dimensions of the cuboid are 15 cm by 10 cm by 3.5 cm. The radius of each of the depressions is 0.5 cm and the depth is 1.4 cm. Find the volume of wood.

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Calculating Volume in Practical Applications

The task of calculating the volume of a wooden pen stand, which is in the shape of a cuboid with four conical depressions, is a practical application of geometry in everyday objects. This problem is not just a mathematical exercise; it’s a real-world scenario that can be encountered in fields like carpentry, design, and manufacturing. The pen stand has specific dimensions: a length of 15 cm, a width of 10 cm, and a height of 3.5 cm, with each conical depression having a radius of 0.5 cm and a depth of 1.4 cm. The challenge is to calculate the volume of wood used in the pen stand, considering the space occupied by the conical depressions.

Understanding the Cuboid Structure of the Pen Stand

The primary structure of the pen stand is a cuboid, a three-dimensional rectangle. The volume of a cuboid is calculated by multiplying its length, width, and height. In this case, the dimensions of the cuboid are 15 cm (length), 10 cm (width), and 3.5 cm (height). This straightforward calculation forms the basis for understanding the total volume of the pen stand before accounting for the conical depressions. The volume of the cuboid represents the maximum amount of wood that could be used in the pen stand.

Analyzing the Conical Depressions

The pen stand features four conical depressions designed to hold pens. Each depression reduces the total volume of wood in the stand. To calculate the volume of each depression, we use the formula for the volume of a cone, which is (1/3)πr²h, where r is the radius and h is the height (or depth) of the cone. The radius of each depression is 0.5 cm, and the depth is 1.4 cm. This calculation is crucial to determine the amount of wood removed from the cuboid to create each depression.

Calculating the Volume of the Conical Depressions
To find the total volume of the conical depressions, we calculate the volume of one cone and then multiply it by four, as there are four depressions in the pen stand. The volume of one conical depression is (1/3)π×0.5²×1.4. Multiplying this by four gives the total volume of wood removed to create the depressions. This step is essential to accurately determine the volume of wood that is actually present in the pen stand.

Total Volume of Wood in the Pen Stand

The final step is to calculate the total volume of wood in the pen stand. This is done by subtracting the total volume of the conical depressions from the volume of the cuboid. By doing this, we account for the space occupied by the depressions and thus determine the actual volume of wood used in the pen stand. This calculation is important for practical purposes such as material estimation, cost calculation, and design efficiency in woodworking and manufacturing.

The Importance of Geometry in Everyday Objects

In conclusion, calculating the volume of wood in a pen stand with conical depressions exemplifies the practical application of geometric principles in everyday objects. This exercise not only reinforces the understanding of how to calculate the volumes of composite shapes but also highlights the importance of these calculations in real-world applications, particularly in design and manufacturing. It showcases how mathematical concepts are applied in practical scenarios, emphasizing the role of geometry in the design and creation of functional and aesthetic objects. This problem-solving approach is not just about numbers and formulas; it’s about understanding the spatial properties of objects and their applications in the real world.

Discuss this question in detail or visit to Class 10 Maths Chapter 12 for all questions.
Questions of 10th Maths Exercise 12.2 in Detail

A solid is in the shape of a cone standing on a hemisphere with both their radii being equal to 1 cm and the height of the cone is equal to its radius. Find the volume of the solid in terms of π.
Rachel, an engineering student, was asked to make a model shaped like a cylinder with two cones attached at its two ends by using a thin aluminium sheet. The diameter of the model is 3 cm and its length is 12 cm. If each cone has a height of 2 cm, find the volume of air contained in the model that Rachel made.
A gulab jamun, contains sugar syrup up to about 30% of its volume. Find approximately how much syrup would be found in 45 gulab jamuns, each shaped like a cylinder with two hemispherical ends with length 5 cm and diameter 2.8 cm.
A pen stand made of wood is in the shape of a cuboid with four conical depressions to hold pens. The dimensions of the cuboid are 15 cm by 10 cm by 3.5 cm. The radius of each of the depressions is 0.5 cm and the depth is 1.4 cm. Find the volume of wood in the entire stand.
A vessel is in the form of an inverted cone. Its height is 8 cm and the radius of its top, which is open, is 5 cm. It is filled with water up to the brim. When lead shots, each of which is a sphere of radius 0.5 cm are dropped into the vessel, one-fourth of the water flows out. Find the number of lead shots dropped in the vessel.
A solid iron pole consists of a cylinder of height 220 cm and base diameter 24 cm, which is surmounted by another cylinder of height 60 cm and radius 8 cm. Find the mass of the pole, given that 1 cm³ of iron has approximately 8g mass.
A solid consisting of a right circular cone of height 120 cm and radius 60 cm standing on a hemisphere of radius 60 cm is placed upright in a right circular cylinder full of water such that it touches the bottom. Find the volume of water left in the cylinder, if the radius of the cylinder is 60 cm and its height is 180 cm.
A spherical glass vessel has a cylindrical neck 8 cm long, 2 cm in diameter; the diameter of the spherical part is 8.5 cm. By measuring the amount of water it holds, a child finds its volume to be 345 cm³. Check whether she is correct, taking the above as the inside measurements, and π = 3.14.