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ALL PHYSICS DOUBTS - POST HERE !!

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rhea:

--- Quote from: Adzel on May 26, 2010, 07:38:12 pm ---@ rhea:

The function of a slip ring is to make one or more continuous electrical connections from points in a stationary unit to points in a rotating section. Electrical connections on slip rings can be for both power and data signal connections.

--- End quote ---

hey thanks =)

just another doubt:

Ac generator/ DC motor, which one takes half-turns?

Vin:

--- Quote from: ang3l on May 26, 2010, 07:09:14 pm ---Hehe yeah a pendin Q  ::)

http://www.freeexampapers.us/IGCSE/Physics/CIE/2009%20Nov/0625_w09_qp_32.pdf

Q9 part c all  ::)

--- End quote ---

9 c)i)
ok so the initial temperature of water was 21.1 which rose to 22.9 so the diff. = 22.9-21.1 = 1.8*C
Initial temperature of metal was 100*C and it fell to 22.9*C .. y 100 because it was taken out from boiling water which is 100*C
so diff. = 100 - 22.9 = 77.1*C

ii) Thermal energy(Q) = mass * specific heat capacity * temp. change

= 0.2kg * 4200 J / (kg K) * 1.8*C
= 1512 J

iii) Heat lost by water  = heat gained by metal
Q = 1512 J
m = 0.05kg
temp.change = 77.1*C

Q = mc(theta)
c = Q/m(theta)

c = 1512/0.05*77.1

  = 392.22
  =392 J/kg*C

iv) Heat lost in surroundings

rhea:

--- Quote from: NightHawkerr on May 26, 2010, 07:53:43 pm ---Hey one question, A box full of matches.. Does it have internal(thermal) energy or chemical energy?

--- End quote ---

chemical, i guess.

Adzel:

--- Quote from: rhea on May 26, 2010, 07:53:54 pm ---hey thanks =)

just another doubt:

Ac generator/ DC motor, which one takes half-turns?



--- End quote ---

Split rings = half turns = DC motor

thenewkid™:

--- Quote from: NightHawkerr on May 26, 2010, 07:53:43 pm ---Hey one question, A box full of matches.. Does it have internal(thermal) energy or chemical energy?

--- End quote ---
chemical energy

sry didnt notice u ppl hd answered

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