Directions:  Draw free-body diagrams with all forces and given information.  Write summation of x and y components.  Solve the problems showing all work. 

 

  1. A block of mass 5.00 kg rests on a horizontal surface where the coefficient of sliding kinetic friction between the two is 0.200. A string attached to the block is pulled horizontally, resulting in a 2.00-m/s2 acceleration by the block. Find the tension in the string and the normal force. (g = 9.80 m/s2)

 

Free-body diagram                   

 

 

 

 

 

 

Summation of components                     SFx                                                                                        SFy      (each set =ma)                                    

 

 

 

 

 

 

 

 

 

 

  1. A 15-kg block is on top of a level frictionless surface and is attached by a light string to a 5.0-kg hanging mass where the string passes over a massless frictionless pulley. If g = 9.8 m/s2, what is the tension in the connecting string?  Also find the normal force and acceleration of the system when in motion.

 

 

Free-body diagrams (two)                     

 

 

 

 

 

 

 

 

Summation of components    SFx                                        SFy                                    SFy                                                                   

(each set =ma)                                     

 

3.  A man pulls a 100 kg sled at a constant velocity across a horizontal snow surface. If a force of 80 N is being applied to the sled rope at an angle of 53° to the ground, what is the force of friction between sled and snow?  Find normal force also. 

 

Free-body diagram                   

 

 

 

 

 

 

 

 

Summation of components                     SFx                                                                                        SFy      (each set =ma)                                    

 

 

 

 

 

 

 

 

 

 

4.  A 20‑kg traffic light hangs midway on a cable between two poles 40 meters apart. If the sag in the cable is 4.0 meters, what is the tension in each side of the cable (T1, T2, T3)?  The angle between the horizontal and the sagging cable on each side is 11o. 

 

 

Free-body diagram                   

 

 

 

 

 

 

 

 

 

 

Summation of components                     SFx                                                                                        SFy      (each set =ma)