Answer:
-17.89 m/s (or 17.89m/s downward)
edit:
if we round this to the nearest whole number, the answer is -18m/s (or 18m/s downward)
Explanation:
recall that one of the equations of motion can be expressed as:
v² = u² + 2as,
where
v = final velocity = given as 20 m/s
u = initial velocity = given as 7.0 m/s
a = acceleration. Since it is freefalling downwards, the acceleration it would experience would be the acceleration due to gravity = -9.81 m/s²
s = displacement (we are asked to find)
simply substitute the known values into the equation:
v² = u² + 2as
20² = 7² + 2(-9.81)s
400 - 49 = -19.62s
-19.62s = 351
s = 351/-19.62
s = -17.8899
s = -17.89 m/s (or -18 m/s rounded to nearest whole number)
