Blocks A and B of masses 19 kg and 15 kg, respectively, are connected by a rope that passes over a light frictionless pulley as shown. Horizontal surface is rough. The static and kinetic friction coefficients are 0.40 and 0.20, respectively. External forces P and Q act on block B as shown. In the figure, the force P is equal to 60 N. What is the approximate maximum value of Q force at which the system remains at rest?

Arunner is jogging at a steady 3.6 km/hr. when the runner is 2.9 km from the finish line, a bird begins flying from the runner to the finish line at 14.4 km/hr (4 times as fast as the runner). when the bird reaches the finish line, it turns around and flies back to the runner. even though the bird is a dodo, we will assume that it occupies only one point in space, i.e., a zero-length bird. how far does the bird travel? (b) after this first encounter, the bird then turns around and flies from the runner back to the finish line, turns around again and flies back to the runner. the bird repeats the back and forth trips until the runner reaches the finish line. how far does the bird travel from the beginning? (i.e. include the distance traveled to the first encounter)