practice

1. A supertanker doesn't come with brakes. Using engines alone, it takes a loaded supertanker 13 km (8 miles) to stop. A typical vessel of this class has a gross mass of about 150 million kilograms (150 thousand tons) and a cruising speed of 50 kph (30 mph). Determine the average stopping force applied to the ship.
2. Write something else.
3. Write something different.
4. Write something completely different.

numerical

1. Before a transparent material can be approved for use as a windshield in an airplane, it must first pass the "bird-impact resistance" test. A genuine (dead) or artificial chicken is accelerated to aircraft cruising speeds from the mouth of an air cannonand aimed at the windshield prototype. If the material shows any significant form of damage it fails the test. Each part of this problem contains an except from a USAF News Agency report.
   1. "Aircrews … find nothing funny about bird strikes. A strategically placed feathered bullet can wreak the same amount of damage as a laser-guided missile. The impact of a four-pound bird at 500 mph lasts less than a thousandth of a second, but can generate forces exceeding 100,000 pounds." Verify this statement; that is, that show that such a collision would indeed exert the force claimed.
   2. "They fire gelatin-molded, artificial birds weighing four pounds apiece, out a compressed air, 30 foot barrel cannon, which can shoot at speeds up to 900 mph. Three lasers and photodetectors measure the artificial chicken's velocity, while three cameras shoot the impact at 6,000 frames per second." Calculate the force exerted by the cannon on the chicken.