Answer:
16 m/s
Step-by-step explanation:
Mass of rock = 2 kg
Potential energy = 256 J
Kinetic energy of the stone at rest would be zero.
This means, the total energy of the rock would be 256 J.
By law of constant energy, kinetic energy of the rock would be equal to the potential energy of the rock (at rest).
Which means,
½ mv² = 256
mv² = 256 × 2
v² = 256×2/2 (m = 2kg)
v² = 256
v = √256
v = 16 m/s
Hence, speed of the rock just before it hits the ground would be 16 m/s.
Option Four
