Relative velocity = Speed of object 1 + Speed of object 2 = 20 m/s + 30 m/s = 50 m/s.

Relative speed = Speed of object 1 + Speed of object 2 = 40 m/s + 60 m/s = 100 m/s.

Relative speed = 40 m/s + 60 m/s = 100 m/s. Time = Distance / Relative speed = 200 m / 100 m/s = 2 s.

F = G * (m1 * m2) / r^2 = (6.67 x 10^-11) * (1 * 1) / (1^2) = 6.67 x 10^-11 N.

If the distance is halved, the gravitational force increases by a factor of four, as it is inversely proportional to the square of the distance.

Using conservation of momentum and kinetic energy, the final velocity of the 3 kg object can be calculated to be 3 m/s.

Two parallel wires carrying currents in the same direction will attract each other due to the magnetic fields they produce.

Two parallel wires carrying currents in the same direction experience an attractive force between them.

The electric potential energy increases as the charges are brought closer together if they are of the same sign.

When two polarizers are oriented at 90 degrees to each other, no light can pass through, resulting in zero intensity.

When two polarizers are oriented at 90 degrees to each other, no light passes through, resulting in zero intensity.

When two polarizers are at 90 degrees to each other, no light passes through, resulting in minimum intensity.

Using Ohm's law, I = V/R, for the 4 ohm resistor, I = 12V / 4 ohms = 3 A.

Using Ohm's law, V = I * R, the voltage drop across the 4 ohm resistor is V = 2 A * 4 ohms = 8 V.

Resistivity is a property of the material, not the configuration; it remains 5 x 10^-6 Ω·m.

Total resistance in series is the sum: R_total = R1 + R2 = 5 + 10 = 15 Ω.

Resistivity is a property of the material and does not change with series or parallel connections.

The moment of inertia depends only on the mass distribution and shape, not on the angular velocity.

In constructive interference, the amplitudes of the waves add up, resulting in a doubled amplitude.

A phase difference of π radians results in destructive interference.

Constructive interference occurs when the path difference is nλ, where n is an integer.

Destructive interference occurs when the phase difference is π rad.

For destructive interference, the resultant amplitude is zero when two equal amplitudes cancel each other out.

Maximum intensity (I_max) = 4A^2 for two waves of equal amplitude A.

Constructive interference results in a wave of higher amplitude.

Constructive interference occurs when two waves meet in phase, resulting in a wave with a larger amplitude.

In series, the total resistance is the sum of individual resistances.

When unpolarized light passes through a polarizer, 50% of the light intensity is transmitted.

According to Malus's law, the intensity of transmitted light is half of the original intensity when unpolarized light passes through a polarizer.

When unpolarized light passes through a polarizer, 50% of the light intensity will emerge, according to Malus's law.