A model rocket accelerates upward from the ground with a constant acceleration, reaching a height of 50 m in 8 s. What is the speed (in m/s) at a height of 50 m?A: 1.07×101 B: 1.25×101 C: 1.46×101 D: 1.71×101 E: 2.00×101

The  value is  

Explanation:

From the question we are told that

    The  height is  

    The  time taken is  

From the equation of motion we have  that

Here u = 0  because the rocket started at rest

=>  

=>    

Also from the kinematic equation we have that

=>  

=>  

the correct choice is a .

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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.