Question

The formula `S = ut - 1/3 at^2` where S is the distance travelled, u is the initial velocity, a is the acceleration and t is the time is ______.

Options

• only dimensionally correct.

• dimensionally incorrect.

• dimensionally and numerically correct.

• dimensionally and numerically wrong.

Answer 1

The formula `S = ut - 1/3 at^2` where S is the distance travelled, u is the initial velocity, a is the acceleration and t is the time is only dimensionally correct.

Explanation:

`S = ut - 1/2 at^3`

term 1 = ut ⇒ LT^-1 T = L

term 2 = `1/2at^2` ⇒ LT^-2 T² ⇒ L

So, given relation only dimensionally correct.