Velocity, acceleration, and time for free fall (2-13)

Question 1 of 4

Question

$\textbf{Velocity at time}$ $\boldsymbol{t}$ of an object in free fall

{"title":"velocity at time t","description":"Correct!","type":"correct","color":"#99CCFF","code":"[{\"shape\":\"rect\",\"coords\":\"1,26,28,54\"}]"} {"title":"velocity at time = 0","description":"Wrong","type":"incorrect","color":"#ffcc00","code":"[{\"shape\":\"rect\",\"coords\":\"101,20,133,60\"}]"} {"title":"Acceleration due to gravity","description":"Incorrect","type":"incorrect","color":"#333300","code":"[{\"shape\":\"rect\",\"coords\":\"229,19,261,67\"}]"} {"title":"time at v sub y","description":"Incorrect","type":"incorrect","color":"#000080","code":"[{\"shape\":\"rect\",\"coords\":\"263,11,289,56\"}]"}

Question

$\textbf{Time}$ at which the object has position $v_y$

{"title":"velocity at time t","description":"Incorrect","type":"incorrect","color":"#99CCFF","code":"[{\"shape\":\"rect\",\"coords\":\"1,26,28,54\"}]"} {"title":"velocity at time = 0","description":"Incorrect","type":"incorrect","color":"#ffcc00","code":"[{\"shape\":\"rect\",\"coords\":\"101,20,133,60\"}]"} {"title":"Acceleration due to gravity","description":"Incorrect","type":"incorrect","color":"#333300","code":"[{\"shape\":\"rect\",\"coords\":\"229,19,261,67\"}]"} {"title":"time at v sub y","description":"Correct!","type":"correct","color":"#000080","code":"[{\"shape\":\"rect\",\"coords\":\"263,11,289,56\"}]"}

Question

$\textbf{Acceleraton due to gravity}$

{"title":"velocity at time t","description":"Incorrect","type":"incorrect","color":"#99CCFF","code":"[{\"shape\":\"rect\",\"coords\":\"1,26,28,54\"}]"} {"title":"velocity at time = 0","description":"Incorrect","type":"incorrect","color":"#ffcc00","code":"[{\"shape\":\"rect\",\"coords\":\"101,20,133,60\"}]"} {"title":"Acceleration due to gravity","description":"Correct!","type":"correct","color":"#333300","code":"[{\"shape\":\"rect\",\"coords\":\"229,19,261,67\"}]"} {"title":"time at v sub y","description":"Incorrect","type":"incorrect","color":"#000080","code":"[{\"shape\":\"rect\",\"coords\":\"263,11,289,56\"}]"}

Question

$\textbf{Velocity at time}$ $\boldsymbol{t\ = 0}$ of an object in free fall

{"title":"velocity at time t","description":"Incorrect","type":"incorrect","color":"#99CCFF","code":"[{\"shape\":\"rect\",\"coords\":\"1,26,28,54\"}]"} {"title":"velocity at time = 0","description":"Correct!","type":"correct","color":"#ffcc00","code":"[{\"shape\":\"rect\",\"coords\":\"101,20,133,60\"}]"} {"title":"Acceleration due to gravity","description":"Incorrect","type":"incorrect","color":"#333300","code":"[{\"shape\":\"rect\",\"coords\":\"229,19,261,67\"}]"} {"title":"time at v sub y","description":"Incorrect","type":"incorrect","color":"#000080","code":"[{\"shape\":\"rect\",\"coords\":\"263,11,289,56\"}]"}

Review

Note the minus sign in front of each term containing $g$ , which is a reminder that the acceleration is always downward, in the negative $y$ direction. If a freely falling object is rising, it slows down; if the object is descending, it speeds up.