# Thread: Hi all, New here and needing help

1. ## Hi all, New here and needing help

Hi,

I am currently doing my HNC and I am struggling with a few maths questions I hope you can all help me with.

1. The power (P) dissipated in a resistor (R) which is subjected to a voltage (V) across its terminals is given by the well-known formula;
𝑃=𝑉2𝑅
Since you are new to the company your new Line Manager is unsure of your capabilities, and has asked you to use the dimensions of P and V to determine the dimensions of R.

2. A guitar string, made by your Musical Instruments division, has mass (m), length (&#119897 and tension (F). It is proposed by one of your junior colleagues that a formula for the period of vibration (t) of the string might be;
𝑡=2𝜋√𝑚3𝑙𝐹
Use dimensional analysis to show your colleague that this formula is incorrect.

2. ## Re: Hi all, New here and needing help Originally Posted by Green294 Hi,

I am currently doing my HNC and I am struggling with a few maths questions I hope you can all help me with.

1. The power (P) dissipated in a resistor (R) which is subjected to a voltage (V) across its terminals is given by the well-known formula;
𝑃=𝑉2𝑅
Since you are new to the company your new Line Manager is unsure of your capabilities, and has asked you to use the dimensions of P and V to determine the dimensions of R.

2. A guitar string, made by your Musical Instruments division, has mass (m), length (&#119897 and tension (F). It is proposed by one of your junior colleagues that a formula for the period of vibration (t) of the string might be;
𝑡=2𝜋√𝑚3𝑙𝐹
Use dimensional analysis to show your colleague that this formula is incorrect.
How far have you gotten with these? Let us know and we can pick it up from there.

-Dan

3. ## Re: Hi all, New here and needing help

1. P =V^2/R

(L^0.5M^0.5T^−1)^2/l^-1T = MT

4. ## Re: Hi all, New here and needing help

I found power = Work/time and worked down to [ML^2T^-3]
Voltage = W/Q worked down to ML^2T^-2/IT
Brought R to the left and P tp right R=V^2/P
R = (ML^2T^-3/ML^2I-1T-3)/ML^2T-3

The working out seems out after this can anyone guide me from here