If 'x' is distance, 't' is time, and 'a' is acceleration, the expression x = at + a²t³ is dimensionally incorrect. Which term needs correction to make it dimensionally correct for x?

6 views 1 helpful Updated Jul 27, 2026
Appears in NEET UG
Solution ✔ Verified
  • A'at' should be 'a²t'
  • B'a²t³' should be 'at²'
  • C'at' should be 'sqrt(a)t'
  • D'a²t³' should be 'a/t'
Explanation

The dimension of x is [L]. The dimension of 'at' is [LT^-2][T] = [LT^-1], which is incorrect for length. The dimension of 'a²t³' is ([LT^-2]²)[T³] = [L²T^-4][T³] = [L²T^-1], also incorrect. For the equation to be dimensionally correct, each term must have dimensions of [L]. If the first term were 'at²', then [LT^-2][T²] = [L]. So, if 'at' is meant to be 'at²', then [B] is the correct fix for the second term, given 'at' is implicitly assumed to be the correct part. Let's reassess. The question is "Which term needs correction...". The whole equation is wrong. We need to find an option that makes the equation dimensionally sound if one of the terms is corrected. Let's check the proposed options. If 'at' is dimensionally wrong, and 'a²t³' is dimensionally wrong. The core of the question is to identify the common term (L) and fix one of the other terms to match L. The question implies one specific correction makes it dimensionally correct. If we consider the desired dimension of each term to be [L]: [at] = [LT^-2][T] = [LT^-1] (Incorrect) [a²t³] = [L²T^-1] (Incorrect) Let's assume the question implicitly refers to the standard kinematic equation and identifies a correction to make it fit for x. A common form is x = v0t + (1/2)at². So the second term should be [at²] = [L]. Option B states 'a²t³' should be 'at²'. If we replace 'a²t³' with 'at²', the equation becomes x = at + at². This still has [LT^-1] + [L], which is dimensionally inconsistent. This question is tricky or ill-posed if I assume standard equations. Let's assume only one of the terms is to be corrected to match 'x'. If the question intends that *one specific change* makes the whole equation dimensionally correct, then both terms must individually become [L]. Original terms: [at] = [LT^-1], [a²t³] = [L²T^-1]. If B is correct, then 'a²t³' becomes 'at²'. Equation becomes x = at + at². Dimensions are [L] = [LT^-1] + [L]. Still incorrect.

Was this solution helpful?
1
Practice MCQs on Units & Dimensions — test yourself with instant answers. Start Practising