Question

A Stone thrown from the top of a building is given an initial velocity Of 20.0 metre per second straight upward determine the time in second at which the stone reaches its maximum height. ( Take sec2 g=9.8m/s)

A) 2.8
B) 2.04
C) 1.67
D) 2.7​

Answer 1

• B) 2.04

Step-by-step explanation:

Given that,

• Initial velocity of the stone (u) = 20.0 m/s

• Acceleration due to gravity (g)= -9.8 m/s² [upward motion]

• Final velocity of the stone
  `\sf{(v_(max))=0\:m/s}`

We know that,

`{\boxed{\sf{v=u+gt}}}`

[ Put values ]

`\begin{gathered} \implies \sf \: {0} \: = {20} + ( - 9.8) * t \\ \\ \implies \sf \: 0 = 20 - 9.8t \\ \\ \implies \sf \: 9.8t = 20 \\ \\ \implies \sf \: t = (20)/(9.8) \\ \\ \implies \sf \: t = 2.04\end{gathered}`

Therefore, the time at which the stone reaches its maximum height will be 2.04 s.