1. A plane starts from rest and aceelerates in a straight line along the ground before take-off. It
moves 600 m in 12 s. Calculate the distance
moved during the twelfth second.

s=600 m

t=12 s

s=0.5*a*t² (initial speed V0=0)

a=(2*s)/t²

a=(2*600)/12²

a≈8.33 m/s²

L= s(t2=12s)-s(t1=11s) -> (distance during the twelfth second)

L=0.5*a*(t2²-t1²)

L=0.5*((2*s)/t²)*(t2²-t1²)

L=0.5*((2*600)/12²)*(12²-11²)

L ≈ 95.83 m

c. newton's third law of motion

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.