A crew working with dynamite to clear a road blasted a large rock straight up into the air with an initial velocity of 170 ft/sec. The rock reaches a height of s(t): -16t² + 170t after t seconds. = a) What is the velocity of the rock at t seconds? v(t) = -32t+170 ft/s Previe = -32t + 170 ft v(t) = b) What is the velocity of the rock when it is 170 feet above the ground on the way up Round to 2 decimal places.