# Search results

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...