Final answer:
The shape of the disk described in the question is a circle, appropriate for Physics at the High School level. The volume of a sphere is given by the formula 4³/3, which is commonly discussed in physics contexts along with rotational motion topics.
Step-by-step explanation:
The question specifies a circular disk of radius r that is attached to a rotating shaft. Given the options, the shape of the disk is 1) Square, 2) Triangle, 3) Circle, 4) Rectangle, the correct shape of the disk is a Circle.
The subject area of this question is Physics, as it concerns topics related to circular motion and rotational dynamics. The information provided in the question is typical for a student studying at the High School level. Understanding the nature of the objects in rotational motion is essential for solving physics problems involving angular dynamics, moment of inertia, angular velocity, and other related topics.
In response to CHECK YOUR UNDERSTANDING 1.5, the formula for the volume of a sphere is 4³/3, which is the expression for the volume of a sphere of radius r. The other expression, 4², represents the surface area of a sphere.