Question

Question 1: Two boxes placed on each other are on a conveyor belt. Belt starts moving right. only top block slips a bit. Which is correct about forces on the bottom block?

Choices of forces on only the bottom block:
1. only kinetic friction (pointing left)
2. only static friction (pointing left)
3. only static friction (pointing right)
4. both kinetic and static friction (each pointing opposite directions)

Question 2:
Position vector: [5.0m +(2.0 m/s^2)t^2]i + [4.0m - (3.0m/s)t]j

Using the position vector, find the speed at 2 seconds

Thank you

Answer 1

For visualising rhe forces on the blocks, we draw the FBD for the blocks. Both static and kinetic friction acting on the lower block in opposite directions.

We know that velocity is defined as the derivative of the position vector. Now speed can be found as magnitude of velocity.