# Thread: Physics Dimensional Analysis problem

1. ## Physics Dimensional Analysis problem

(a) Suppose that the displacement of an object is related to time according to the expression
x
= Bt^2. What are the dimensions of B?
1)L^2/L
2)T^2/L
3)L × T^2
4)L/T^2
5) L/T

(b) A displacement is related to time as x = A sin(2πft), where A and f are constants. Find the dimensions of A. [Hint: A trigonometric function appearing in an equation must be dimensionless.]
1)L/T
2)T/L
3)L
4)L × T

Hey guys I've used the site in the past and it has helped me tremendously. I'm now in a physics class and its going to be a long uphill struggle for me. These are 2 problems out of 15 from some homework I have and if someone can break it down for me that would be more than wonderful.

2. ## Re: Physics Dimensional Analysis problem

Originally Posted by FactoringAnguish
(a) Suppose that the displacement of an object is related to time according to the expression
x
= Bt^2. What are the dimensions of B?
1)L^2/L
2)T^2/L
3)L × T^2
4)L/T^2
5) L/T
$x$ is a displacement so its dimensions are $\rm{[L]}$. so you have a dimensional expression:

$\rm{[L]=[B][T]^2}$

so:

$\rm[B]=...\ ?$

CB

3. ## Re: Physics Dimensional Analysis problem

Originally Posted by CaptainBlack
$x$ is a displacement so its dimensions are $\rm{[L]}$. so you have a dimensional expression:

$\rm{[L]=[B][T]^2}$

so:

$\rm[B]=...\ ?$

CB
B= L/T^2 so #4 yes? I was so caught up with breaking down B into its own components rather than solving for B.

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# suppose that the didplacrment of an object is related to the time according to the expression X=Bt squared. what are the dimensions of B?

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