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1. Homework help

Ok- I'm sorry to keep asking about the same questions but I tried to apply the law of conservation of energy to the two problems and I'm not coming out with the right answers: 72) I understand that PE at the top of the hill will be zero because the object is already moving, and it will also be...
2. Homework help

Also, I calculated #72 out, and I'm getting 5.0 m/s but I don't understand how the speed is the same?!
3. Homework help

ok- i can figure out # 72 now but How do I apply the "force of friction retards his motion by doing 2500 J of work" in #79>?
4. Homework help

No- that makes me more confused!
5. Homework help

I'm having problems with the following two problems. Thank you for any help! 72) A skiier coasts down a very smooth 10-meter high slope. If the speed of the skiier on the top of the slope is 5.0m/s, what is his speed at the bottom of the slope? I calculated 2gy= v2 and plugged in v= sq root...
6. Force and tension

I am having some trouble with two problems- thanks for any help! 71) A .2kg ball is dropped from 10 m above the beach, leaving an impression in the sand 5.0 cm deep. What is the average force acting on the ball by the sand? So far I have converted 5.0cm to .05m. I calculated Fg= .2 kg...
7. What is the car's vertical velocity

I am having problems with the following questions. Any help would be greatly appreciated! 19) Automobile travels at constant speed of 60 km/hr (16.7m/s), 800 m along a straight highway that is inclined 5 degrees to the horizontal. An observer notes only the vertical motion of hte car. What is...
8. More questions

As for #2a) I've calculated v2 = 100 km/hr + 2 (-6.5 m/s2)(20 m), v2 = 360, v= 18.9, 100-18.9 = 81.1 km/hr #2b) vx= vox + axt making 81.1 = 100 + (-6.5)t making t= 2.9 sec #3) I've tried calculating average velocity and then plugging that answer in for x= average velocity x time for both of...
9. More questions

i don't know why I'm having so many problems but I greatly appreciate the help! 1) A train normally travels at a uniform speed of 72 km/hr on a long stretch of straight, level track. On a particular day, the train must make a 2.0-min stop at a station along this track. If the train decelerates...
10. Newton's 3rd Law homework help

I'm having trouble with the following problems: 1) A student throws a water balloon down at his math professor walking on the sidewalk. He drops a balloon from 18.0 meters above the ground when the profesor is 1.00 meter from the point directly beneath the window. IF the professor is 170 cm...
11. Magnitude and average velocity

und I go to University of North Dakota
12. Magnitude and average velocity

I am having a problem with the following question: A spider crawls from corner A to corner B in 30 minutes. The distance between AC (C chosen as a half-way point) is 27 meters, the spider turns right and the distance between CB is 21 meters. a) What is its average speed? and b) what is the...