Alarge flat block of mass 7 m rests on a level, smooth tabletop (µk ≈ 0). on top of it is a much smaller block of mass m, with a coefficient of static friction between the two blocks of µs. if the small block is pulled horizontally with constant force f, we want both blocks to slide together across the table without slipping on each other.
what is the largest acceleration that the system can be given in terms of µs and g?
1. f − µs g/ 8
2. f /8 m
3. µs g /7
4. µs g
5. 7 µs g /8
6. 8 µs g

3. µs g /7

Explanation:

The largest Force appear when the maximal friction Force is required.

Second Newton law for the small block:

Second Newton law for the Big Block:

jupiter is the largest planet in our solar system, having a mass and radius that are respectively, 318 and 11.2 times that of earth. suppose that an object falls from rest near the surface of each planet and that the acceleration due to gravity remains constant during the fall. each object falls the same distance before striking the ground. determine the ratio of the time of fall on jupiter to that on earth.

not too sure thinking all accelerations are pointed down