The resistance of the lamp is apparently 50V/2A = 25 ohms.
When the circuit is fed with more than 50V, we want to add
another resistor in series with the 25-ohm lamp so that the
current through the combination will be 2A.
In order for 200V to cause 2A of current, the total resistance
must be 200V/2A = 100 ohms.
The lamp provides 25 ohms, so we want to add another 75 ohms
in series with the lamp. Then the total resistance of the circuit is
(75 + 25) = 100 ohms, and the current is 200V/100 ohms = 2 Amps.
The power delivered by the 200V mains is (200V) x (2A) = 400 watts.
The lamp dissipates ( I² · R ) = (2² · 25 ohms) = 100 watts.
The extra resistor dissipates ( I² · R) = (2² · 75 ohms) = 300 watts.
Together, they add up to the 400 watts delivered by the mains.
CAUTION:
300 watts is an awful lot of power for a resistor to dissipate !
Those little striped jobbies can't do it.
It has to be a special 'power resistor'.
300 watts is even an unusually big power resistor.
If this story actually happened, it would be cheaper, easier,
and safer to get three more of the same kind of lamp, and
connect THOSE in series for 100 ohms. Then at least the
power would all be going to provide some light, and not just
wasted to heat the room with a big moose resistor that's too
hot to touch.
Answer:
7200 kg.m/s
Explanation:
According the law of conservation of linear momentum, the sum of momentum before and after collision are equal.
Using this principle, the sum of initial momentum will be given as p=mv where p is momentum, m is mass and v is velocity
Initial momentum
Mass of whale*initial velocity of whale + mass of seal*initial seal velocity
Since the seal is initially stationary, its velocity is zero. By substitution and taking right direction as positive
Initial momentum will be
1200*6+(280*0)=7200 kg.m/s
Since both initial and final momentum should be equal, hence the final momentum will also be 7200 kg.m/s
9.1 basic since > 7
1.2 VERY acidic << 7
<span>5.7 acidic < 7
</span>
