How Things Work: An Introduction to Physics week 7

In this blog you will find the correct answer of the Coursera quiz How Things Work: An Introduction to Physics week 7 mixsaver always try to brings best blogs and best coupon codes

Week- 7

Bumper Cars


1. A meteor is streaking toward city hall and will hit the building in a few second. As it moves through the sky, what physical quantities is the meteor carrying with it? [Ignore any effects due to air or Earth’s gravity]


2. You have a midnight craving for ice cream and are walking quickly through your pitch-black apartment when you collide with the wall. You come to a complete stop. Fortunately, your interior decorator mounted a thick woolen tapestry (wall-hanging) on the concrete wall and that soft tapestry saves you from injury. Compare the momentum you transferred while coming to a stop on the tapestry-covered wall to the momentum you would have transferred if you had come to a stop on the bare concrete wall.


3. A car traveling at 60 mph (100 km/h) veers off the road and hits a tree. The car immediately comes to a complete stop. Fortunately, the airbag inflates and the driver comes to a stop in the airbag instead of coming to a stop on the steering wheel. Hitting the airbag rather than the steering wheel saves the driver’s life because the driver


4. A diver stands upright at the edge of the 10 meter platform at the Olympics. The diver jumps off the platform, folds into a ball shape, completes 3.5 somersaults, unfold out of the ball shape, and plunges head-first into the water. Compare the diver’s angular momentum about the diver’s center of mass at three different moments while that diver is not touching anything: (a) before folding into a ball shape, (b) while ball-shaped, and (c) after unfolding out of the ball shape [Note that the diver’s weight, which acts at the diver’s center of gravity, produces zero torque on the diver about the diver’s center of mass. Ignore any effects due to the air.]


5. The chef at a pizza restaurant tosses a spinning disk of pizza dough into the air. As the disk stretches outward in midair and its diameter increases, what happens to the disk’s angular momentum and angular velocity about the disk’s center of mass? [Note that the disk’s weight, which acts at the disk’s center of gravity, produces zero torque on the disk about the disk’s center of mass. Ignore any effects due to the air.]


6. You are riding on a large carousel at an amusement park and you are enjoying the moving scenery as the carousel spins about its center of rotation. The ride comes to an end and the carousel gradually slows to a stop. Why does it take so long for the carousel to stop rotating?


7. A “lazy susan” is a disk-shaped rotating platform that a restaurant places at the center of a large dining table. Dishes of food are placed on the lazy susan and diners can rotate the lazy susan by hand to bring various dishes closer to them. A large torque exerted for a short time makes the motionless platform begin rotating rapidly, but that dangerous technique risks tipping over some of the food dishes. How can you make the same motionless platform and dishes begin rotating just as rapidly, but with a smaller, safer torque?


8. To win a big prize at the fair or festival, all you have to do is toss a basketball into a bucket located about 10 feet (3 meters) in front of you and have the basketball remain in the bucket. The rigid bucket cannot move and it opens toward you. However, the bucket is tilted upward just enough that the basketball will remain in it if someone places the basketball in the bucket by hand. You try a dozen times to get the basketball to stay in the bucket, but it keeps bouncing back out of the bucket. Why is it so difficult for the basketball to come to rest in the bucket?


9. You have just added a massive stone sculpture to your modern art collection. Unfortunately, the people who delivered the sculpture accidentally set it on its side. What barbarians! To tip the sculpture onto its proper base, you transfer as much momentum as you can to the highest point on the sculpture. You accomplish this transfer (successfully, I might add) by running full speed toward the sculpture and


10. Your dynamic sculpture combines magnets, springs, and elastic bands with a variety of moving parts, including levers, pulleys, and pendulums. When someone jostles those parts, a complicated series of motions occurs and predicting how things will proceed seems nearly impossible. You point out, however, that there is a simple rule governing the motion of each part at any moment in time. That rule is that each part





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