The picture shows a physics lab set up. When the index card is quickly pulled away from the glass in a horizontal direction, why does the disk fall straight down into the glass? a kinetic friction b static friction c inertia d equilibrium
The correct answer is c) inertia.
When the index card is quickly pulled away from the glass in a horizontal direction, the disk falls straight down into the glass due to the principle of inertia.
Inertia is the tendency of an object to resist a change in its state of motion. In this case, the disk was initially at rest on the index card, and when the index card is quickly pulled away horizontally, it imparts a sudden change in motion to the disk. However, due to its inertia, the disk resists this change and continues moving in its initial downward path, falling straight into the glass.
Choice a) kinetic friction is not applicable here because there is no surface contact between the disk and the glass that could create kinetic friction.
Choice b) static friction is not applicable either since there is no surface contact and the disk is not experiencing any force due to static friction.
Choice d) equilibrium is also not the correct answer as the situation described involves a change in motion, not a state of balance or stability.