Forces and acceleration

  • #1

Homework Statement


Mass m1=31.7 kg is on a horizontal surface, connected to mass m2= 5.30 kg by a light string as shown. The pulley has negligible mass and no friction. A force of 216.9 N acts on m1 at an angle of 29.3deg. The coefficient of kinetic friction between m1 and the surface is 0.221. Determine the upward acceleration of m2.

physicsprblm.jpg




Homework Equations


F=ma
Fn = mg-Fsin(theta)
Fcos(theta)-(uk)(Fn) = ma

The Attempt at a Solution


First I found the normal force of M1. Fn = mg-Fsin(theta). I found Fn to be 204.513 N. Next, I found the acceleration of M1 by using [Fcos(theta)-(uk)(Fn)] / m = a. I got ax to be 4.54 m/s^2. I assumed that the acceleration would be the same for M2 but its not.
 

Answers and Replies

  • #2
Doc Al
Mentor
45,089
1,396
You forgot to consider the string tension acting on the block. (The accelerations of M1 and M2 must be the same--they are connected by a string.)
 

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