Question

A ball is thrown vertically upward and attains a maximum height of $100$ m. It was thrown with a speed

• A. 9.8 m/s
• B. 44.3 m/s
• C. 19.6 m/s
• D. 98 m/s

Answer 1

The correct option is B

44.3 m/s

Step 1 Given:

Height =$100$ m

$$\begin{gathered} a=-g=-9.8m/s² \\ V=0 \end{gathered}$$

Step 2 Solution:

$$\begin{gathered} v^2=u^2+2as \\ 0=u^2+2(-9.8)100 \\ {u}^2=(2\times 9.8\times 100) \\ u=\sqrt{1960} \\ u=44.27 \\ u=44.3m/s \end{gathered}$$

Hence, option (b) is correct.