What is the mass, in kilograms, of a person whose weight on Earth is 670 N (about 150 pounds)? The measurement for gravity on Earth is 9.8 meters per second squared (m/s2). Enter your answer as a number, rounded to the nearest tenth, with the appropriate unit, like this: 4.2 kg

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