Question

A stone is vertically thrown upward with the velocity of 72km/hour. Find the maximum height reached and time taken to reach the height.

Answer 1

Answer:

Initial velocity = u = 20 m/s  

Final velocity = v = 0              [ at maximum height , v = 0 ]

Acceleration due to gravity(g)  in this case , is taken as negative.

This is because , when the direction of motion of object is opposite to "g" , then value of g is taken as -ve

hence ,

g = -9.8 m/s²

Let's use the formula :-

[h = height ]

v² -u² = 2gh

0² - 20² = 2*-9.8*h

-400 = -19.6h

h = -400/-19.6

 = 20.408 m [ approximately ]

The stone will go 20.408 metres high  before it begins to fall