AP Physics C: Rotational Dynamics Review - 2 of 2 (Mechanics)

The video tutorial covers key concepts in rotational dynamics, including torque, cross product, and equilibrium. It provides an example of calculating the cross product using unit vectors and discusses translational and rotational equilibrium. The tutorial explains angular momentum and its relation to torque, using Newton's second law. It concludes with an example problem on the conservation of angular momentum, emphasizing the importance of identifying the axis of rotation.

What is the correct order of vectors in the torque equation involving a cross product?

• R cross F

• R dot F

• F dot R

• F cross R

Why is the cross product not commutative?

• Because it involves addition

• Because the order of vectors affects the direction of the result

• Because it involves subtraction

• Because it involves multiplication

In a 3D cross product calculation, what is the first step?

• Multiply the vectors

• Find the determinant of a matrix

• Subtract the vectors

• Add the vectors

What condition must be met for an object to be in translational equilibrium?

• Net torque is zero

• Net torque is non-zero

• Net force is zero

• Net force is non-zero

How is angular momentum related to torque according to Newton's laws?

• Torque is the derivative of angular momentum

• Angular momentum is the derivative of torque

• Angular momentum is the integral of torque

• Torque is the integral of angular momentum

What is the equation for the angular momentum of a particle?

• R cross mass times velocity

• R dot mass times velocity

• Mass times velocity

• R times velocity

What must be true for angular momentum to be conserved in a system?

• Net internal torque is zero

• Net internal force is zero

• Net external torque is zero

• Net external force is zero

In the example problem, what is the significance of the height Y?

• It is the mass of the cylinder

• It is the radius of the cylinder

• It is the distance from the axis of rotation

• It is the initial velocity of the gum

What happens to the final angular velocity if the initial velocity of the gum increases?

• It decreases

• It becomes zero

• It remains the same

• It increases

How does a larger radius of the cylinder affect the final angular velocity?

• It doubles the final angular velocity

• It has no effect

• It decreases the final angular velocity

• It increases the final angular velocity