A certain type of film requires an exposure time of 0.013 s with an f /1.8 lens setting. Another type of film requires twice the light energy to produce the same level of exposure. What f - stop does the second type of film need with the 0.013 s exposure time? (Common f - stops are 1, 1.2, 1.4, 1.8, 2, 4, 8, 11)

If a rock is thrown upward on the planet mars with a velocity of 12 m/s, its height (in meters) after t seconds is given by h = 12t − 1.86t2. (a) find the velocity of the rock after two seconds. m/s (b) find the velocity of the rock when t = a. 12−3.72a m/s (c) when will the rock hit the surface? (round your answer to one decimal place.) t = s (d) with what velocity will the rock hit the surface? m/s