An astronaut lands on a distant planet and places a mathematical pendulum with a length of 50 cm. He measures that the pendulum makes 100 oscillations in 136 sec. What is the gravity acceleration on that planet.

Answer 1

T = 136s/100cycles. = 1.36 s./cycle.

T^2 = 39.48*L/g = (1.36)^2.
L/g = 0.0468, g = 0.50/0.0468 = 10.7 m/s^2.