# Help me ace my physics test tomorrow!

#### nissanfreak

I am looking over my study and have a few questions. How would I solve some of these questions?

1) An ice skater moving at 12m/s coasts to a halt in 95m on an ice surface. What is the coefficient of friction between the ice and skates? QUESTION: is the formula to use for this always going to be -mew with little k = a with little x divided by g? Will the answer be -.077?

2) A car exits from the expressway to a circular exit ramp that posts a maximum exit speed of 35mph (15.6 m/s). If the typical coefficient of static friction between tires and pavement is 0.4, what is the radius of the exit ramp? QUESTION: Is this the formula i need to use to solve this R=Vsquared/mew times g ? The answer I got is 62.018m. Am i doing this right?

3) A pail of water is rotated in a vertical circle of radius 1m. What is the minimum speed of the pail at the top of the circle if no water is to spill out?
QUESTION: Is this the right formula Vsquared=RG? The answer I got is 3.03 m/s(squared) Am I on the the right track with this one?

Please help me do good on my test tomorrow. Any and all help would be greatly appreciated

Related Introductory Physics Homework News on Phys.org

#### teknodude

Hard to tell if its right without seeing the work, but these don't take alot of calculations, so....

1) An ice skater moving at 12m/s coasts to a halt in 95m on an ice surface. What is the coefficient of friction between the ice and skates? [/B] QUESTION: is the formula to use for this always going to be -mew with little k = a with little x divided by g? Will the answer be -.077?
The answer is right. Also I would't say the formula is always going to be that.

A car exits from the expressway to a circular exit ramp that posts a maximum exit speed of 35mph (15.6 m/s). If the typical coefficient of static friction between tires and pavement is 0.4, what is the radius of the exit ramp? [/B] QUESTION: Is this the formula i need to use to solve this R=Vsquared/mew times g ? The answer I got is 62.018m. Am i doing this right?
correct

3) A pail of water is rotated in a vertical circle of radius 1m. What is the minimum speed of the pail at the top of the circle if no water is to spill out?
QUESTION: Is this the right formula Vsquared=RG? The answer I got is 3.03 m/s(squared) Am I on the the right track with this one?

#### geosonel

1) coeff of friction generally given with (+) number. so here μk=+0.077
2) looks good. can you derive the formula which you stated?
3) basic formula is (mV2)/R = mg
so you're right that V2 = Rg
or V = √(Rg) = √(9.8) = 3.13 m/sec

### Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving