... The top branch of the 3-branched parallel block ... the 9 and 6 in series ...
is equivalent to a single resistor of 15 ohms.
... The 3-branched parallel block boils down to (30, 10, and 15) in parallel.
That's (1/30 + 1/10 + 1/15)⁻¹ = 5 ohms.
... The 5-ohm-equivalent block and the 20-ohm resistor form a
voltage divider across the battery.
The voltage across the 5-ohm-equivalent block is (5/25 x 30v) = 6v .
... The top branch of the block is equivalent to a (9 + 6) = 15-ohmer.
With 6v across its ends, the current through that branch is (6/15) = 0.4A .
... With 0.4A flowing through it, the 9-ohm resistor is dissipating
I²R = (0.4A)² (9 ohms) = (0.16 A²) (9 ohms) = 1.44 W (choice-3)
We have F = kx or ma = kx where m and k are constants. Therefore, if x is halved, a must be halved too.
Structural constraint is the answer :)
Explanation:
Though the diagram that is mentioned in the questions is not given. I have given general information related to the Earth's magnetic axis with respect to geographic/rotational axis.
Axis is an imaginary line around which a body rotates. The rotational axis of the Earth enters into and exits from the Earth at two points namely: North and South pole.
We know that the Earth behaves like a huge bar magnet so just like the bar magnet it must also have magnetic axis and poles. Earth has north magnetic pole and south magnetic pole. It has a strong magnetic field as well known as magnetosphere.
The interesting point about magnetic axis is that it is not same as rotational axis. In fact it makes an angle with the rotational axis. This is known as magnetic inclination. This inclination varies at different points on Earth.
Another interesting point is that the geographic and magnetic poles are opposite. That means near the geographic north pole we have the magnetic south pole and vice versa.
(Mass does not affect the pendulum's swing. The longer the length of string, the farther the pendulum falls; and therefore, the longer the period, or back and forth swing of the pendulum. The greater the amplitude, or angle, the farther the pendulum falls; and therefore, the longer the period.)
