Question

A spring gun of spring constant 90 N/cm is compressed 12 cm by a ball of mass 16 g. If the trigger is pulled, the velocity of the ball is –

• A. 50 ms^–1
• B. 90 ms^–1
• C. 40 ms^–1
• D. 60 ms^–1

Answer 1

Answer: (B)

90 ms^–1

Answer 2

$\frac{1}{2}$mv² = $\frac{1}{2}$kx²

$\frac{1}{2}$ (16 × 10^–3) v² = $\frac { 1 } { 2 }$ $\frac{90}{10^{–2}}$ (144 × 10^–4)

v² = 8100 or v = 90 m/s