Speed of train = 72 km/h = 20 m/s. Time = 20 s. Distance = Speed × Time = 20 m/s × 20 s = 400 m. Length of platform = 400 m - 180 m = 220 m.

Speed in m/s = 72 * (1000/3600) = 20 m/s. Distance = Speed × Time = 20 m/s × 30 s = 600 m. Length of platform = 600 m - 200 m = 400 m.

Relative speed = Speed of train + Speed of bird = 90 km/h + 45 km/h = 135 km/h.

Let the distance be d. Time taken by first train = d/90. Time taken by second train = d/120. Setting up the equation gives d = 150 km.

Let the distance be d. Time taken by first train = d/70, second train = d/90. They meet when d/70 = d/90 + 0.5. Solving gives d = 100 km.

Let the time taken by the first train be t hours. Distance = speed * time. 80t = 100(t - 0.5). Solving gives t = 2 hours, so distance = 80 * 2 = 160 km.

Relative speed = Speed of train - Speed of man = 72 km/h - 6 km/h = 66 km/h.

Relative speed = Speed of train - Speed of man = 72 km/h - 6 km/h = 66 km/h.

Total distance = Length of train + Length of platform. If length of train is L, time = (L + 300)/20 m/s. Assuming L = 300 m, time = (300 + 300)/20 = 30 seconds.

First, convert speed to m/s: 72 km/h = 20 m/s. Using a = (v - u)/t = (0 - 20)/5 = -4 m/s².

First, convert speed to m/s: 60 km/h = 60/3.6 = 16.67 m/s. Using the formula: acceleration = (final velocity - initial velocity) / time = (0 - 16.67) / 5 = -3.33 m/s², approximately -3 m/s².

First convert speed to m/s: 72 km/h = 20 m/s. Using the formula: acceleration = (final velocity - initial velocity) / time = (0 - 20) / 10 = -2 m/s².

First convert speed to m/s: 72 km/h = 20 m/s. Using the formula: acceleration = (final velocity - initial velocity) / time = (0 - 20) / 10 = -2 m/s².

First convert velocity to m/s: 36 km/h = 10 m/s. K.E. = (1/2)mv² = (1/2)(1000 kg)(10 m/s)² = 50000 J.

Speed = distance / time = 120 km / 2 h = 60 km/h.

Distance = speed × time = 72 km/h × 0.5 h = 36 km.

Time = distance / speed. Convert speed to m/s: 72 km/h = 20 m/s. Time = 180 km / 72 km/h = 2.5 hours.

Relative speed = 90 - 60 = 30 km/h. Distance apart after 1 hour = 30 km.

The voltage ratio in a transformer is given by the turns ratio. Therefore, V_primary/V_secondary = N_primary/N_secondary = 100/50 = 2, which means V_primary = 2 * V_secondary.

A transformer is designed to increase or decrease the voltage in an AC circuit through electromagnetic induction, depending on the turns ratio of the primary and secondary coils.

A transformer is used to increase or decrease the voltage in an AC circuit based on the turns ratio of its coils.

A transformer operates on the principle of electromagnetic induction, transferring energy between coils through a changing magnetic field.

Using tan(30°) = height/20, we have 1/√3 = height/20. Therefore, height = 20/√3 ≈ 11.55 m.

Using tan(45°) = height/shadow, we have 1 = height/20. Therefore, height = 20 m.

Height = shadow * tan(angle) = 20 * tan(30°) = 20 * (1/√3) = 20√3 meters.

Distance = height / tan(angle) = 15 / tan(30°) = 15√3 meters.

Using the formula λ = v/f, we find λ = 340 m/s / 440 Hz = 0.7727 m, approximately 0.77 m.

The period T is the reciprocal of frequency f. T = 1/f = 1/440 Hz = 0.00227 s.

The period T is the reciprocal of frequency f. T = 1/f = 1/440 Hz = 0.00227 s.

The speed of sound in air at 20°C is approximately 343 m/s. The wavelength λ is given by λ = v/f. Thus, λ = 343/440 ≈ 0.78 m.