Well, first of all, the formula for finding potential energy is; PE=mgh Where; m is the mass g is the gravitational force or acceleration due to gravity h is the height. Anyway, according to the question, the mass is 1kg, the acceleration due to gravity has a constant value of 10ms² . And the height is 3m. Now you just have to use all these in the formula. So; mgh= 1 x 10 x 3. That will be 30. And the unit of potential energy is Joule. So the answer is 30 joules. Hope i helped. Have a nice day.
For a first order reaction, the half life is inversely proportional to the rate constant. The formula is half life = ln(2)/k = 0.693/k where k is the rate constant
