A 5 kg block is connected to a 10 kg block by a cord on ahorizontal, frictionles

Question

A 5 kg block is connected to a 10 kg block by a cord on ahorizontal, frictionless surface. the 10 kg block is pulledhorizontally by a force of 30 N. What is the tension in the cordconnecting them?


Two blocks of masses m1=1kg and m2 = 2 kg areconnected by a massless cord passing over a massless, frictionlesspulley. The pulley is pulled up with a force f=50N. What are theaccelerations of the two masses with respect to the ground?


Could someone please help me figure these out, and could you offerany suggestions on attacking similar problems like these Thanks!

Explanation / Answer

First question... the acceleration is foundby    acc = total force / totalmass = 30 / 15 = 2 . Then, the tension just pulls on the second block so... .          Tension = mass * acc = 5 * 2 =   10 Newtons . For the second question... the forces acting on the pulleyare: .               50 N up,    tension + tension (one on eachside) down. . So we have     50 N = 2 *tension . Tension = 25 N . This is the tension that acts on each block. So we can write,for each block:    Tension - mg = ma . Or...     a = T/m - g . And we get: .     Form1       acceleration = 25 / 1   - 9.8   =    15.2m/s2 .    Form2        acceleration = 25 / 2    -9.8   =    2.7m/s2 .    Form2        acceleration = 25 / 2    -9.8   =    2.7m/s2

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