Physics MCQs thread.

[yubakkk]

hassan
u can compare with
1/2mu^2= vq
v=pd
u =speed

 

[Xthegreat]

how 2 do it??

B is the ans.

ignore the pulley cause no friction force is mentioned.
the torque to move the disc is 900x0.2 =180Nm-1
so now, to use the spindle to move the disc which have a torque of 180Nm-1
F x 1.2 = 180
F = 150 N.

 

[yubakkk]

thanks xthegreat............

 

[ShootingStar]

what if the friction force is mentioned...

 

[abdullah181994]

see...F=qV/D...F=ma
qV/D=ma.....let V/D--->> A constant K....SO ma=Kq...rearranging....a=Kq/m....means a is proportional to q/m ratio....now chill out...apply this nd u ll get B

but correct answer is C

 

[arlery]

what if the friction force is mentioned...

Is the answer C?

 

[ShootingStar]

what if the friction force is mentioned...

Is the answer C?

Answer is A

 

[arlery]

Oh yeah my bad, I used g as 9.8 first.

Anyway, here goes:

Solve it by forming 2 simultaneous equations:

For the 8kg box, T-6 = 8a
For the 2 kg box, mg-T = 2a
2(10) - T = 21 ---> 20 - T =2a

Solve them simultaneously and you get a = 1.4 m/s

 

[hassam]

oh sorry abdullah uu apply my technique it was C...my explanation is CORRECT !!!

 

[arlery]

Why is the answer B?

 

[ShootingStar]

Oh yeah my bad, I used g as 9.8 first.

Anyway, here goes:

Solve it by forming 2 simultaneous equations:

For the 8kg box, T-6 = 8a
For the 2 kg box, mg-T = 2a
2(10) - T = 21 ---> 20 - T =2a

Solve them simultaneously and you get a = 1.4 m/s

ah i see.. thnx

 

[histephenson007]

 

[hassam]

post again./...full is nt visible

 

[arlery]

post again./...full is nt visible

can you solve my doubt on the previous page?

 

[ShootingStar]

The answer is D..how? :unknown:

 

[histephenson007]

Ok, posted it again
how the hell are we supposed to know the units of specific heat capacity???

 

[histephenson007]

The answer is D..how? :unknown:

We know that.......... I = A^2 , and I = 1/(x^2)
so, from substitution, we can get (A^2) = 1/(x^2) ......... A=1/x

From the given data, we can form 2 equations:
1........... 8=1/r
2............x=1/2r

from the formula 1, we can get that r=1/8
If we put the value of r into the 2nd equation, x = 1/2r = 8/2 = 4

 

[ShootingStar]

The answer is D..how? :unknown:

We know that.......... I = A^2 , and I = 1/(x^2)
so, from substitution, we can get (A^2) = 1/(x^2) ......... A=1/x

From the given data, we can form 2 equations:
1........... 8=1/r
2............x=1/2r

from the formula 1, we can get that r=1/8
If we put the value of r into the 2nd equation, x = 1/2r = 8/2 = 4

oh ok... I get it

 

[ShootingStar]

Ok, posted it again
how the hell are we supposed to know the units of specific heat capacity???

Is it A?

 

[histephenson007]

no, its B.
any1 plz explain...