Ahiker walks with constant speed of 1.2 m/s around a roundabout with diameter of 30 m. what is the centripetal acceleration of the hiker? 2. in training, astronauts ride in a device in which they experience a centripetal acceleration of 3.00g where g = 9.80 m/s2 as they would when the booster rickets separate from their space shuttle. specifically, the astronaut is fastened securely at the end of a mechanical arm that then turns at constant speed in a horizontal circle. determine the rotation rate, in revolutions per second, required to give an astronaut a centripetal acceleration of 3.00g while in circular motion with radius 9.45 m. 3. if a stone is revolved a sling of length 0.600 m at the rate of 8.00 rev/s, what is its centripetal acceleration? 4. extra credit: a train slows down as it rounds a sharp horizontal turn, slowing from 130.0 km/h to 40.0 km/h in the 10.0 s that it takes to round the bend. the radius of the curve is 150 m. compute the acceleration at the moment the train speed reaches 40.0 km/h. assume it continues to slow down at this time at the same rate.