A 6.40 kg block rests on a 12.5 kg block as shown in the diagram.

The interface between the lower mass and the table is frictionless, but
there is friction (static friction μS and kinetic friction μK) between the two
blocks. A horizontal force F
r
acts on the UPPER block and causes both
blocks to accelerate. The acceleration of both blocks when they begin to
slip is 2.0 2 s
m .
(i) Calculate the force F at the time when the blocks start to slip.
6.40 kg
12.5 kg
F
(ii) Calculate the coefficient of static friction μS.

1 answer

3. A spaceship of mass 175,000 kg travels from the Earth to the Moon along a line that passes through the center of the
Earth and the center of the Moon. At what distance from the center of the Earth is the force due to the Earth twice the
magnitude of the force due to the Moon? If the spaceship has double the mass, will this position move toward the
earth or moon?