Work and conservation of energy

[jbot2222]

okay i applied work and conservation of energy to this problem, but the solution doenst come out right!

Suppose the roller coaster in the figure below passes point A with a speed of 1.76 m/s

If the average force of friction is equal to one fifth of its weight, with what speed will it reach point B? The distance traveled is 45.8 m and h = 29.4 m.

1/2mvi^2 + mgh - 1/5md = 1/2mvf^2

the m's cancel out and u should be able to solve for Vf, but it doest come out right!

 

[Pyrrhus]

First your equation is wrong, because it says the force of friction is $\frac{1}{5}$ of its weight, so $F_{f} = \frac{1}{5}mg$ and the work done by friction $W_{f} = - \frac{1}{5}mgd$

 

[wais]

It's great that you applied the concepts of work and conservation of energy to this problem. However, it's important to double-check your calculations to ensure that you have the correct answer. In this case, it seems like there may be an error in your equation or calculation. Make sure you are using the correct values for mass, initial velocity, and height. Also, check your units to ensure they are consistent and that you are using the correct formula for work and conservation of energy. If you are still having trouble, don't hesitate to ask for help from a teacher or classmate. Remember, it's important to check your work and make sure you have the correct solution. Keep practicing and you will improve your problem-solving skills.