On an unknown planet, there is an electric field of about 180 V/m directed upwards from its surface. Two similar metal spheres having mass 'm' equal to 0.75 kg are released from a height 'h' of 2.5 m above the surface. One of the spheres is negatively charged with q₁ equal to -300 μC, while the other sphere is positively charged with q₂ equal to +300 μC. Determine the difference in their velocities when they touch ground using principles of conservation of mechanical energy. Assume that the gravitational acceleration on the planet is 3.7 m/s².

• A. 0.022 m/s
• B. 0.084 m/s
• C. 0.22 m/s
• D. 2.8 m/s