CHAPTER 9

1. (P.263 Prob.26) Far in space, where gravity is negligible, a 425-kg rocket traveling at 75 m/s fires its engines. Figure P9.26 shows the thrust force as a function of time. The mass lost by the rocket during these 30 s is negligible.
   a. What impulse does the engine impart to the rocket?
   b. At what does the rocket reach its maximum speed? What is the maximum speed?
   
2. (P.264 Prob.32) Three identical train cars, coupled together, are rolling east at 2.0 m/s. A fourth car traveling at 4.0 m/s catches up with the three and couples to make a four-car train. A moment later, the train cars hit a fifth car that was at rest on the tracks, and it couples to make a five-car train. What is the speed of the five-car train?
3. (P.264 Prob.36) A firecracker in a coconut blows the coconut into three pieces. Two pieces of equal mass fly off south and west, perpendicular to each other, at 20 m/s. The third piece has twice the mass as the other two. What are the speed and direction of the third piece?
4. (P.264 Prob.44) Two 500-g blocks of wood are 2.0 m apart on a frictionless table. A 10-g bullet is fired at 400 m/s toward the blocks. It passes all the way through the first block, then embeds itself in the second block. The speed of the first block immediately after ward is 6.0 m/s. What is the speed of the second block after the bullet stops?
5. (P.266 Prob.66) Challenge Problem. A 75-kg shell is fired with an initial speed of 125 m/s at an angle 55° above horizontal. Air resistance is negligible. At its highest point, the shell explodes into two fragments, one four times more massive than the other. The heavier fragment lands directly below the point of the explosion. Iif the explosion exerts forces only in the horizontal direction how far from the launch point does the lighter fragment land?