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I have this problem:

A 4.0 kg block is given an initial speed of 8.0 m/s at the bottom of a 20° incline. The frictional force that retards its motion is 15.0 N. (a) If the block is directed up the incline, how far does it move before stopping? (b)Will it slide back down the incline?

I've managed to get part (a) which was 4.51m but I'm not sure how to start part (b)..

The coefficient of Kinetic Friction was 0.407

Any ideas?

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closed as too localized by dmckee Mar 4 '13 at 1:04

This question is unlikely to help any future visitors; it is only relevant to a small geographic area, a specific moment in time, or an extraordinarily narrow situation that is not generally applicable to the worldwide audience of the internet. For help making this question more broadly applicable, visit the help center.If this question can be reworded to fit the rules in the help center, please edit the question.

I'd like to draw your attention to what our FAQ says about homework-like questions: "Physics - Stack Exchange is not a homework help site. If you have a question about a homework problem, or any problem of an educational nature, narrow it down to the specific concept that is giving you trouble and ask about that. You can find more information about acceptable homework questions on our meta site". There is a good conceptual questions here. Can you edit this to be that question? – dmckee Mar 4 '13 at 1:04

Some potentially useful hints/questions:

  1. When the ball gets to the top of its trajectory, it is no longer moving.

  2. Draw a free body diagram for when the ball is at the top.

  3. Under what condition on the forces will it move back down after stopping at the top?

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