A simple rule to bear in mind is that all objects (regardless of their mass) experience the same acceleration when in a state of free fall. When the only force is gravity, the acceleration is the same value for all objects. On Earth, this acceleration value is 9.8 m/s/s.
Gravity ALWAYS does that, and electrostatic force does it when two objects have opposite charges.
Answer: 4
Explanation: speed= distance/time
The specific heat capacity of a substance is the amount of energy needed to change the temperature of 1 kg of the substance by 1 degree Celsius.