General Knowledge - Physics - Discussion

Discussion Forum : Physics - Section 1 (Q.No. 15)
15.
Out of the following pairs, choose the pair in which the physical quantities do not have identical dimension?
Pressure and Young's modules
Planck's constant and Angular momentum
Impulse and moment of force
Force and rate of change of linear momentum
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
21 comments Page 1 of 3.

Aravind said:   1 decade ago
@Vivetha.

Impulse is the force acting on a body for a particular time.

Hence impulse is the product of impulse=f*t.

Due to impulse a moment of force occurs that is m*v.

Hence the dimensional formula for them is for impulse [M L T^-1].

AND FOR MOMENT OF FORCE IT IS Newton meter == (kgm/sec^2) *m.

Kgm^2/sec^2.

Deepthi said:   6 years ago
Angular momentum is a rotational representation of linear momentum. So, its Dimension is same as linear momentum ML^2T^-1.

Proton's energy = Planck's constant x Frequency.
Nm*s = Planck's constant since, (1/Freq) = s.
(Kgm/s^2)m*s = Kgm^2/s
Dimension is ML^2T^-1.

Adebayo said:   1 decade ago
Excuse me is the unit of force the same as that of change of linear momentum. Force=ma and /\Momentum=mv-mu. Unit of force is newton(kgm/s^2) while momentum is Kgm/s. Pls are the two entitles thesame? Im really confused, kindly forward your views to me. Thank u!

Vivetha.h said:   1 decade ago
Impulse and the moment of force have identical quantites, just I need a correct explanation, how it I identified? how it is derived? any one can give me a correct explanation, if so, fast as you can possible, ok, wish you all the best, bye.

Getnet Tegenie said:   1 decade ago
You are correct, but you didn't agree with your idea. Young's modulus has the same unit with stress or pressure. So the answer is only choice C which has quantities with different dimensions. The rest all choices have the same dimensions.

Amit Kumar Sahu said:   1 decade ago
Impulse means change in the momentum of a body

i.e. Impulse = Ft = mv - mu

The turning effect of force about the axis of rotation is called moment of force or torque.

So they don't have any units... resulting no dimensions!!

Mohan said:   1 decade ago
B also could be right.

Pressure = Force/Area,
Stress = Force/Area,
Young's modulus = Stress/Strain,

Strain has no units.

So, Pressure and Young's modulus have same dimensions.

Please correct me if I am wrong.

Paul martiins said:   9 years ago
Impulse = ft (the signal recieved by an object)

where f = newton and t = sec unit=(N/sec2).

While moment is returning effect an object makes or is de product of force * distance unit =(N/m2).

Paul said:   9 years ago
From Bohr theory, Angular momentum is equal to plank constant, ie L=nh where n= 1, 2, 3.

Also Angular momentum L = n * Dirac constant divided by 2 pie. Option C is the correct answer.

Mohammad Afzal said:   10 years ago
@Mohan: Force = MLT^-2 and Pressure = Force/area = (MLT^-2)/(L^2).

Hence, Pressure = ML^-1T^-2.

Whereas,

Young's Modulus = Pressure/Length = ML^-2T^-2.


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