You are conducting an experiment inside a train car that may move along level rail tracks. a load is hung from the ceiling on a string. the load is not swinging, and the string is observed to make a constant angle of 45∘ with the horizontal. no forces other than tension and gravity are acting on the load. which of the following statements are correct? statements include: 1. the train is an inertial frame of reference. 2. the train is not an inertial frame of reference. 3. the train may be at rest. 4. the train may be moving at a constant speed in a straight line. 5.the train may be moving at a constant speed in a circle. 6. the train must be speeding up. 7. the train must be slowing down. 8. the train must be accelerating.

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)