Watch the above video and answer the following questions.

1. Anand leaves his house at 8.30 am for his school. The school is 2km away and classes start at 9 am. If he walks at a speed of 2 km/hr for the first kilometre , at what speed should he walks the second kilometre to reach just in time?.

2. A train starting from a railway station and moving with uniform acceleration attains a speed of 40 km/hr in 10 minutes . Find its acceleration.

3. A scooter travelling at 10 m/s speeds up to 20 m/s in 4s . Find the acceleration of the scooter.

4. An object dropped from a cliff falls with a constant acceleration of 10 m/s2 . Find it's speed after 5s seconds it was dropped.

5. A driver of a car A travelling at 52 km/hr applies the brake and the car stops in 5 s . A driver of car B going at 3 km/hr applies brake and the car stops in 10 s. calculate the acceleration of car A and car B . Also find which car has more acceleration than other.

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explanation:

measuring things 1 litre of water

speed of light in vacuum is 300,000 km/s

speed of light in other mediums is given by the expression v = c/n, where c is the speed of light in vacuum and n is the refractive index of medium.

for the first medium v = 200,000 km/s

  so, refractive index of medium = 300000/200000 = 1.5

    1.5 refractive index is usually for glass. so first medium is glass.

for the second medium v = 250,00 km/s

so, refractive index of medium = 300000/250000 = 1.2

    1.2 refractive index is usually for water. so second medium is water.

for the third medium v = 0 km/s

so, refractive index of medium = 300000/0 = ∞

    ∞ refractive index is usually for opaque mediums. so third medium is opaque medium.