Question

A $0.5\, kg$ ball is thrown vertically up with $14 \,m s^{-1}$. It attains a height of $8\,m$. The energy dissipated by air drag acting on the ball during ascent is

• A. 9.8 J
• B. 4.9 J
• C. 10 J
• D. 19.6 J

Answer 1

Answer: (A)

9.8 J

Answer 2

E = $\frac{1}{2}m \upsilon^2 = \frac{1}{2}(0.5)(14)^2$ = 49 J E' = mgh = $0.5 \times 9.8 \times 8 = 39.2$ J Energy lost = E - E' = 49 - 39.2 = 9.8 J