1)
We will simply use the formula time = distance / speed here.
Note that within the calculations, I am actually changing the units.
For example 1 km = 1000 m, so I multipied 150 km/h by 1000 to get 150000 m/h.
Time
= Distance / Speed
= 18.4m / (150 km/h)
= 18.4m / (150000 m/h)
= 0.000122666 h
= 0.000122666 * 60 * 60 s
= 0.4416 s
~ 0.44 s
2)
Note that I am just substituting the value of t found in 1) into the equation s = 4.9t^2 given here.
The answer must be in cm, so once again, we need to convert m into cm.
s
= 4.9(0.4416)^2 m
= 0.955551744 m
= 0.955551744 * 100 cm
= 95.5551744 cm
~ 96 cm
3)
In the question, it is mentioned that the distance fallen will only be 80% of the original fallen distance. Thus, we multiply the answer in 2) by 80%.
Distance fallen
= 80% * 95.5551744 cm
= 0.8 * 95.5551744 cm
= 76.44413952 cm
~ 76 cm