Relative speed = 70 + 50 = 120 km/h. Distance apart after 2 hours = 120 × 2 = 240 km.

Relative speed = 40 + 60 = 100 km/h. Distance apart after 1 hour = 100 km.

Relative speed = 70 + 50 = 120 km/h. Distance apart after 2 hours = 120 * 2 = 240 km.

At the midpoint, the electric fields due to both charges cancel each other out, resulting in a net electric field of 0.

The electric fields due to both charges at the midpoint cancel each other, resulting in a net electric field of 0.

The third charge must be placed between +q and -q, closer to -q to balance the forces.

The electric field is zero at a point closer to -q because the magnitudes of the fields due to both charges will be equal at that point.

Constructive interference occurs when the path difference is an integer multiple of λ.

A phase difference of π radians corresponds to a path difference of λ/2, leading to destructive interference.

Constructive interference occurs when the path difference is an integer multiple of λ, and 0.5λ corresponds to a half wavelength, leading to constructive interference.

Phase difference (Δφ) = (2π/λ) * path difference. For sound in air, λ = v/f. Assuming f = 1000 Hz and v = 340 m/s, λ = 0.34 m. Δφ = (2π/0.34) * 0.5 = π/2 rad.

Phase difference (φ) = (2π/λ) * path difference. Given λ = 1 m, φ = (2π/1) * 0.5 = π rad.

Distance apart = (15 + 20) * 1 = 35 km.

Relative speed = 12 + 15 = 27 km/h. Distance apart after 2 hours = 27 * 2 = 54 km.

Using Coulomb's law, F = k * |q1 * q2| / r². Let q be the charge, then 9 = (9 × 10^9) * (q²) / (1)². Solving gives q = 3μC.

U = k * q1 * q2 / r = (9 × 10^9) * (1 × 10^-6) * (1 × 10^-6) / 1 = 9 × 10^-3 J.

When brought into contact, the charges will redistribute equally, resulting in 0μC on each sphere.

When brought into contact, the charges will redistribute equally, resulting in 0μC on each sphere.

The electric fields due to both charges at the midpoint are equal and opposite, thus they cancel each other out, resulting in 0 N/C.

Potential energy U = k * q1 * q2 / r = (9 × 10^9 N m²/C²) * (5 × 10^-6 C)² / 1 m = 0.225 J.

When two identical spheres are brought into contact, they share their charges equally. Thus, they will have equal positive and negative charges after separation.

In free fall, all objects accelerate at the same rate regardless of mass.

Both will land at the same time as they are thrown from the same height.

Both will hit the ground at the same time as they are thrown from the same height.

All objects hit the ground at the same time if launched from the same height with the same speed.

The range is maximum at 45 degrees; hence, the 30-degree projectile will have a longer range than the 60-degree one.

Both angles will have the same range when launched from the same height.

F = G * (m1 * m2) / r² = (6.67 × 10^-11) * (3 * 4) / (1²) = 8.01 × 10^-11 N

Relative velocity = Velocity of observer 1 + Velocity of observer 2 = 20 m/s + 30 m/s = 50 m/s.

Relative speed = Speed of observer 1 + Speed of observer 2 = 20 m/s + 30 m/s = 50 m/s.