Question Details

The velocity v of a particle at time t is given by b v = at + b/(t+c) , where a, b and c are constants. The dimensions of a, b andc are

Options

A

[L], [LT] and [LT⁻²]

B

[LT⁻²], [L] and [T]

C

[L²], [T] and [LT⁻²]

D

[LT⁻²],[LT] and [L]

Correct Answer :

[LT⁻²], [L] and [T]

Solution :

The correct answer is Option [LT⁻²], [L] and [T].

To find the dimensions of the constants a, b, and c in the given equation, we use the principle of homogeneity of dimensions. According to this principle, the dimensions of each term on both sides of a physical equation must be the same. Only physical quantities with the same dimensions can be added or subtracted.

The given equation is:
v=at+bt+c
where:
- v is the velocity, which has the dimensions of [LT-1].
- t is the time, which has the dimensions of [T].

Step 1: Finding the dimensions of c
In the denominator of the second term, we have the expression t+c. Since time t is added to the constant c, both must have the same dimensions.
Therefore, the dimensions of c must be the same as the dimensions of t:
[c]=[t]=[T]

Step 2: Finding the dimensions of a
According to the principle of homogeneity, the dimensions of the term at must be equal to the dimensions of velocity v:
[at]=[v]
[a][t]=[v]
[a][T]=[LT-1]
Solving for [a]:
[a]=[LT-1][T]=[LT-2]

Step 3: Finding the dimensions of b
Similarly, the dimensions of the term bt+c must also be equal to the dimensions of velocity v:
bt+c=[v]
Since the denominator t+c has the dimensions of time [T], we write:
[b][T]=[LT-1]
Solving for [b]:
[b]=[LT-1][T]=[L]

Conclusion:
The dimensions of a, b, and c are [LT-2], [L], and [T] respectively.

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