AP Physics C Mechanics 3.1 Kinetic Energy Overview

Relate translational kinetic energy to mass and speed, recognizing its scalar nature and dependence on the observer’s reference frame.

Covered syllabus points

3.1.A—Describe the translational kinetic energy of an object in terms of the object’s mass and velocity

[Maximum number: 1]

Mech.2.
A block of mass 2 M rests on a horizontal, frictionless table and is attached to a relaxed spring, as shown in the figure above. The spring is nonlinear and exerts a force $F(x)=-B x^{3}$ , where B is a positive constant and x is the displacement from equilibrium for the spring. A block of mass 3 M and initial speed $v_{0}$ is moving to the left as shown.

Determine an expression for the kinetic energy of the two-block system immediately after the collision.

1 point
Using a proper expression for kinetic energy of the two-block system

\begin{aligned} K & =\frac{1}{2} m v^{2} \\ K & =\frac{1}{2}(5 M)\left(\frac{3}{5} v_{0}\right)^{2} \end{aligned}

For an answer consistent with part (b)

K=\frac{9}{10} M v_{0}^{2}

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Covered syllabus points

3.1 Translational Kinetic Energy question 1