Final answer:
The speed of an object thrown upward with the height function s(t) = -2t^2 + 28t at time t = 4 seconds is calculated by differentiating the function and evaluating it at t = 4 to get 12 meters/second.
Step-by-step explanation:
The question asks for the speed of an object at a particular time when the height function is given. The height of an object thrown upward from the surface of a planet is described by the function s(t) = -2t^2 + 28t. To find the speed, which is the first derivative of the height function with respect to time, we differentiate the given function to get the velocity function v(t) = s'(t) = -4t + 28. By substituting t = 4 into the velocity function, we get v(4) = -4(4) + 28 = -16 + 28 = 12 meters/second. Therefore, the speed of the object at time t = 4 seconds is 12 meters/second.