What Formulas Do I Need to 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

 

[teknodude]

Hard to tell if its right without seeing the work, but these don't take a lot 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?

At a glance your answer is the acceleration, but the question is asking for the speed.

 

[geosonel]

in addition to previous comments:
1) coeff of friction generally given with (+) number. so here μ_k=+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