Difficult Force Problem with changing angle ( )

[DJWise]

Difficult Force Problem with changing angle (please help!)

1. A force F is applied to a crate of mass m on a floor where it has a coefficeint of static friction . Angle theta is intially 0 degrees but is gradually increased so that the force vector rotates clockwise in the figure. During the rotation the magnitude F of the force is continuously adjusted so that the crate is always on the verge of sliding. For coeff. of static friction = 0.70 (a) plot the ratio F/mg versus theta and (b) determine the theta sub infinite at which the ratio approaches an infinite value. (c) Does lubricating the floor increase or deacrease theta sub infinite or is the value unchanged? (d) what is theta sub infinite if the coefficient = 0.60?






3. Please help me set up the problem! I am very confused and don't comprehend the question. If you can just help me start the problem I can probably take it from here. We are having an emergency study session w/ our class tonight and none of us understand this.

 

[LowlyPion]

1. A force F is applied to a crate of mass m on a floor where it has a coefficeint of static friction . Angle theta is intially 0 degrees but is gradually increased so that the force vector rotates clockwise in the figure. During the rotation the magnitude F of the force is continuously adjusted so that the crate is always on the verge of sliding. For coeff. of static friction = 0.70 (a) plot the ratio F/mg versus theta and (b) determine the theta sub infinite at which the ratio approaches an infinite value. (c) Does lubricating the floor increase or deacrease theta sub infinite or is the value unchanged? (d) what is theta sub infinite if the coefficient = 0.60?

3. Please help me set up the problem! I am very confused and don't comprehend the question. If you can just help me start the problem I can probably take it from here. We are having an emergency study session w/ our class tonight and none of us understand this.

One way to approach understanding this problem is to draw a force diagram and write things in terms of the Forces. For instance the x component of force is balanced out by the weight and the y component of the force times u.

Then rearrange your formula with F/mg = ...?

You can then evaluate this relationship as theta varies and as to how you might vary u.

 

[thomate1]

Hello there! It seems like you are struggling with a difficult force problem with changing angle. Don't worry, I am here to help you understand and set up the problem. Let's break down the problem into smaller parts and tackle them one by one.

First, we have a crate with a mass of m on a floor with a coefficient of static friction. This means that the crate will not move unless a force greater than the maximum static friction force is applied. We also have an angle theta that is initially 0 degrees but is gradually increased as the force rotates clockwise.

Next, we need to plot the ratio F/mg versus theta. This means we need to calculate the ratio of the applied force F to the weight of the crate mg at different values of theta. We can do this by using trigonometric functions and the given coefficient of static friction.

Now, we need to determine the theta sub infinite at which the ratio approaches an infinite value. This means we need to find the angle at which the applied force is just enough to overcome the maximum static friction force, causing the crate to start moving. This angle is also known as the angle of repose.

Moving on to part (c), we need to consider the effect of lubricating the floor on theta sub infinite. Lubricating the floor would decrease the coefficient of static friction, making it easier for the crate to start moving. This means that the value of theta sub infinite would decrease as well.

Lastly, we need to find theta sub infinite if the coefficient of static friction is changed to 0.60. This means we need to repeat the calculations we did in part (b) using the new coefficient of static friction.

I hope this helps you get started on the problem. Remember to use the given information and equations to solve for the different parts. Good luck with your study session tonight!