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# Hana calls to her 25 lb. pup, Akasha, who comes racing toward the open door for her midday meal of Power Chow. She is hungry and has reached a speed of 2 m/s, but as she enters through the door she looses her footing and slides across the smooth wood floor which Hana has freshly swept. Hana watches hiding a smile as Akasha careens across the nearly frictionless surface straight toward the 1/2 lb. including lunch. The puppy collides with the bowl and continues to slide at a reduced speed of 1.94 m/s. Hana bursts into a fit of laughter as the bowl shoots out across the floor. What is its velocity? *

5.2) Cinco de Mayo

The McCarty-Jimenez family has decided to open their pond for the season in celebration of Cinco de Mayo. Little Felicia and her twin brother Thomas are afloat atop an inner tube at rest in the middle of the pond. Their older sister, Selena  is floating north at a constant speed of 0.5 ft/s.  Felicia jumps from her tube to her sister’s just as the two tubes pass. Only 1.5 seconds later, Thomas is 2.5 ft west of his initial position. Where will the girls’ tube be? Assume that Selena has twice the mass of each of the twins, and the tubes have negligible mass. *

5.3) Glacier Bay

You and a friend are sea kayaking in the Icy Strait of Alaska. Before you row into Glacier Bay you want to have a discussion about your route around the outskirts of the bay. You, your kayak, and the gear in your kayak combined have a mass of 125 kg, and you row towards your friend at 28 mph west-northwest. Your friend is carrying slightly less gear in her kayak so her combined mass is 116 kg, and she’s gliding through the water at 24 mph northwest. After you’re close enough to pull in and hold onto each other’s kayaks, what is the direction of your two-kayak unit? What is your speed? *

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5.4) Ski Buddies

Jessie skis down a mountain and waits for her friend Maria at the bottom.  Maria skis down the slope, spots Jessie and coasts over to her. Laughing, she mischievously aims at Jessie and an inelastic collision occurs, resulting in their combined masses moving in the same direction that Maria was traveling. If Jessie weighs 137 lbs with her skis and Maria weighs 145 lbs with hers, and they are now moving at 1.3 m/s, what was Maria’s speed just before she got to Jessie? *

5.5) Marbles

Massachusetts State Science Fair, Inc.

You and your pal are eight years old and six years old, playing a game of marbles on the sidewalk. She shoots her lucky blue marble (30 g) at a speed of 0.5 m/s straight at a speckled yellow one (15 g). After the blue marble hits the yellow one it slows to a speed of 0.165 m/s. If the yellow marble is 0.7 m from the edge of the circle, and the concrete surface causes a marble to decelerate at 0.22 m/s per second, will the yellow marble leave the circle? *

5.6) Pups

Two puppies, each about 4 kgs each, are running around outside, when suddenly one stops to watch a butterfly flit overhead. One puppy takes advantage of her companion’s distraction to ambush him from the side at 2.1 m/s, and they roll sideways together. What is the speed of their combined masses? *

5.7) Wild Hearts Have Momentum

In the movie Wild Hearts Can't Be Broken, Sonora, a determined diving girl, listens as a horse named Lightning trots up a ramp at a speed of about 17 mph. Near the top of the ramp, Sonora leaps from a standstill onto Lightning's back before he jumps off the top of the 40-ft-high ramp into the pool of water below. If Lightning weighs 1300 lbs and Sonora weighs 125 lbs, what is Lightning's momentum before Sonora leaps onto his back?  If he continues at a speed of 17 mph after she jumps on, what is Sonora's change in momentum? **

5.8) Trapeze

Paolo and Maria are practicing their brother and sister trapeze act. Paolo (144 lbs) swings down off a platform. When he reaches the bottom of his swing, he is moving 15m/s. At that momentum, Maria (112ilbs), just at the top of her swing, transfers from her trapeze to his. What will be the velocity of Paolo’s trapeze then? *

A 68 kg inline skater is coasting at a rate of 5 m/s along the sidewalk, when she sees a woman’s handbag lying in her path. The woman is ahead of her on the sidewalk and so the skater decides to pick up the bag as she drifts by and then hand it to the woman. She bends down to scoop up the bag, but once she does, notices that the readout on her home-built roller-blade velocity-meter decreases to 4.9 m/s. What does this tell the skater about the approximate mass of the handbag? What will happen to the skater’s velocity once she has handed the bag off to the woman (assuming she does so while coasting by)? *

5.10) Photos

Phoebe is printing photographs to give to her friends as graduation presents. She watches as the image of 3 smiling faces comes to life in the developer, and then moves the print to the stop bath. The paper enters the liquid with a speed of about 12 cm/s and collides with a smaller print that was initially at rest on the surface of the stop bath. The two prints stick together and skim across the top of the solution at a rate of 8 cm/s. What can be said about the size of the smaller print in relation to the larger one if we assume that the larger print weighs about 14 grams? Assume that both prints are made on resin-coated paper and so have absorbed no liquid and can travel without friction across the surfaces of the liquid baths. *

5.11) Boarding

You are out skateboarding when you approach a hill. You decide you would like to try and coast up the hill by getting all your momentum on level ground. So you place your board just before the foot of the hill, then you back up to get a running start. You acquire a sprint of 5.5 m/s just as you jump onto the board. If the board is 4.5 kg, what is the speed of you and your board just after you jump? *

Your cousin, who appreciates cookies but doesn’t particularly enjoy baking, buys frozen cookie dough that is already formed into round balls.  She spills them onto the counter as she attempts to put them on the baking sheet and they spill in all directions.  If one ball with mass 2m sliding 60 degrees north of east at 15 cm/s and another ball with mass m sliding 30 degrees west of south at 30 cm/s collide and stick together, what is their joint velocity (magnitude and direction) after the collision? *

Jana Stump, WNBA

Players from the National Wheelchair Basketball Association are doing their strengthening exercises with a 15 lb medicine ball. Jana Stump from the USA team is coasting with a speed of 3 m/s down the court when she catches the medicine ball, which was dropped to her from above. Jana Stump's combined mass with the ball and chair is 85 kg. Determine Jana’s new velocity. *

5.14) Mosaics

Richard Bayliss@ http//museums.ncl.ac.uk/alacami/mosaics/mosscham.htm

Anita is in her school art studio. She wants to make a mosaic resembling a famous mosaic of the Basilica for her ceramic assignment. She stands next to the table with her outline on it, and begins to break tiles to gather the pieces to make her mosaic. She drops a tile on the floor; it breaks into three pieces of equal mass, and notices that two pieces seem to travel at the same speed in a 90-degree angle. The third piece disappears under the table. How can Anita calculate how fast and in what direction the third piece went, without looking under the table? **

5.15) Falcon and Sparrow

A peregrine falcon is soaring on the thermals along the Front Range, looking for supper. She spots a sparrow flying horizontally along below her at 10m/s, folds her wings, and dives. When she hits the sparrow, she is moving vertically at 30m/s. If the falcon’s mass is 3kg and the sparrow’s is 50g, what will be their velocity after the hawk strikes the sparrow?**

Momentum Problem Set

Posted on 8/1/05