ANL - Forces on Incline

Forces on Incline

When an object is placed on an incline, problem solving is made easier if we use an axis that is parallel to the slope of the incline. This allows the acceleration of the object to be along one of the two axes, either up or down the slope. This also places the normal force on the axis perpendicular to the slope. Only the weight, mg, of the object needs to be broken into components. The perpendicular component of the weight is given as mgcosθ, and the parallel component is given as mgsinθ. Once the components are determined the second and third laws of motion are applied as in any other problem. Please watch the following presentation that will introduce Forces on Inclines.

Forces on Incline Practice

The following presentation will give you some examples of problems that include inclines when applying Newton's Laws of Motion.

Forces on Incline Self-Assessment

Complete the self-check questions to verify that you understand how to solve problems dealing with forces on inclines.

  1. A 120kg sled is traveling at 15m/s toward a hill that makes an angle of 30o to the horizontal. The sled must cover 25m of flat ground to get to the base of the hill. If the coefficient of friction is 0.17, how far up the hill will the sled get before coming to a stop?

Problem 1 Image

SOLUTION Links to an external site.

  1. A 75kg block sits on a 40o slope. The block is tied to a mass that hangs off the top of the slope.  

Problem 2 Image

  1. If the coefficient of static friction between the block and the slope is 0.25, what is the minimum hanging mass that will keep the 75kg block from moving up or down the slope?
  2. The rope is now cut. What is the acceleration of the block if the coefficient of kinetic friction between the block and the slope is 0.45?

SOLUTIONS Links to an external site.

  1. Two blocks are pushed up a 25o incline at constant velocity by a force of 350N.  The top block has a mass of 50kg, and the bottom block has a mass of 25kg.

Problem 3 Image

  1. What is the coefficient of friction between the blocks and the incline?
  2. What is the force P between the two blocks?

SOLUTIONS Links to an external site.

Forces on Incline Practice Problems

Download Forces on Incline Practice Problems Links to an external site. for more practice. 

Download solutions Links to an external site. to the practice problems. 

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