202202081217 Dynamics Figures (Elementary) Q6

13. Two identical trolleys are connected by a light string and pulled by a force as shown. Assuming the surface to be frictionless,

(a) calculate the acceleration of the two trolleys;

(b) find the tension in the string.

_{Extracted from B. Kennedy. (2001). Higher Physics Progressive Problems.}

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Solution.

We draw three free-body diagrams of i. ; ii. ; and iii. :

In respective diagrams there are three equations of motion.

By Newton’s second law,

:

we have

Answers. (a) acceleration ; (b) tension .