Which of the following procedures demonstrates repetition? A.
Jeremiah measures the mass of five different strips of metal. He places the strips in five different test tubes filled with hydrochloric acid. He observes if heat and bubbles are produced after the metal strips and acid are combined.
B.
Marco places a toy car at the top of a ramp. He releases the car and measures how long it takes for the car to reach the bottom of the ramp. Then, he returns the car to the top of the ramp, releases the car again, and makes an additional measurement.
C.
Cynthia monitors the growth rate of her pet turtle. She measures the length and weight of her turtle every Sunday over the course of six months.
D.
Kasey performs a scientific investigation on the effects of using soda instead of water to hydrate plants. Caleb uses

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the minimum constant speed at which she can catch the train is 2.7 m/s

given:

acceleration = 0.6

time = 4.5 s

to find:

velocity = ?

formula used:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

solution:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

v = 0 + (0.6 × 4.5)

v = 2.7 m/s

the minimum constant speed at which she can catch the train is 2.7 m/s

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.