Theory question 106
DynamicsThree forces −63j, (32.14i + 38.3j) and (14i − 24.25j) act on a body of mass 5kg. Find, correct to one decimal place, the:
(a) magnitude of the resultant force;
(b) acceleration of the body.
Show the model answer
Model answer
(a) R = (32.14 + 14)i + (38.3 − 63 − 24.25)j = 46.14i − 48.95j
|R| = √(46.142 + 48.952) = √4525.0 ≈ 67.3 N
(b) a = |R|/m = 67.27/5 ≈ 13.5 ms−2
Explanation
Add the i parts and the j parts separately.