Final answer:
The potential energy of the cinder block on the platform 18 m high is calculated using the formula PE = mgh. Plugging in the mass of 8 kg, the acceleration due to gravity of 9.81 m/s², and the height of 18 m, the energy is found to be 1,440 J.
Step-by-step explanation:
The potential energy (PE) of the cinder block can be calculated using the formula PE = mgh, where m is the mass, g is the acceleration due to gravity (9.81 m/s² on Earth), and h is the height of the platform from the ground. Using the values given: m = 8 kg, g = 9.81 m/s², and h = 18 m, the potential energy can be calculated as PE = 8 kg × 9.81 m/s² × 18 m, which equals 1,411.44 Joules. When rounded to three significant figures, the answer is 1,410 Joules. Therefore, the correct option is B) 1,440 J, assuming a rounding to the nearest tens is acceptable.