Which of the following events does not involve a change in angular momentum?

1. A spinning ice skater drawing in her arms to increase her rotational speed.

2. A child walking along the perimeter of a merry-go-round as it rotates.

3. A child walking towards the center of a spinning merry-go-round.

4. A ball rolling down a ramp without slipping.

5. A hockey puck sliding without friction on the surface of an icy pond.

To determine which event does not involve a change in angular momentum, we need to understand the concept of angular momentum and how it changes in each scenario.

Angular momentum is the rotational momentum of an object and is given by the equation L = Iω, where L is the angular momentum, I is the moment of inertia, and ω is the angular velocity.

Let's analyze each event:

1. A spinning ice skater drawing in her arms to increase her rotational speed:
When the ice skater draws in her arms, her moment of inertia decreases. According to the equation L = Iω, if I decreases, the only way to keep angular momentum constant is for ω (angular velocity) to increase. Therefore, there is a change in angular momentum in this event.

2. A child walking along the perimeter of a merry-go-round as it rotates:
In this event, the child is not changing the distribution of their mass or their angular velocity. Since there is no change in either the moment of inertia or the angular velocity, there is no change in angular momentum.

3. A child walking towards the center of a spinning merry-go-round:
When the child walks towards the center of the spinning merry-go-round, their moment of inertia decreases since they are bringing their mass closer to the axis of rotation. Similar to the first scenario, a decrease in moment of inertia requires an increase in angular velocity to keep angular momentum constant. Therefore, there is a change in angular momentum in this event.

4. A ball rolling down a ramp without slipping:
In this scenario, the ball's angular momentum will change if there is a change in moment of inertia or angular velocity. However, since the ball is rolling without slipping, its point of contact with the ramp is fixed, and there is no change in the distribution of mass or the moment of inertia. Therefore, there is no change in angular momentum in this event.

5. A hockey puck sliding without friction on the surface of an icy pond:
In this event, the hockey puck is sliding without any rotational motion. Angular momentum is a measure of rotational motion, so without any rotation, there is no angular momentum to begin with. Therefore, there is no change in angular momentum in this event.

Based on this analysis, the event that does not involve a change in angular momentum is option 5: A hockey puck sliding without friction on the surface of an icy pond.