PHYS 151 Homework #2 Due Thursday, September 7 at 11:55 PM 1. If a subway train is moving to the left (has a negative velocity) and then comes to a stop, what is the direction of its acceleration? Is the acceleration positive or negative? 2. A cyclist rides 8.0 km east for 20 minutes, then he turns and heads west for 8 minutes and 3.2 km. Finally, he rides east for 16 km, which takes 40 minutes. (a) What is the final displacement of the cyclist? (b) What is his average velocity? 3. Sketch the velocity-versus-time graph from the following position-versus-time graph. Position vs. Time 10 - Position (m) Bb bbNONA 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 Time (s) 4. A particle moves in a straight line with an initial velocity of 30 m/s and constant acceleration 30 m/s. (a) What is its displacement at t = 5 s? (b) What is its velocity at this same time? 5. A football quarterback runs 15.0 m straight down the playing field in 2.50 s. He is then hit and pushed 3.00 m straight backward in 1.75 s. He breaks the tackle and runs straight forward another 21.0 m in 5.20 s. Calculate his average velocity (a) for each of the three intervals and (b) for the entire motion