A ball thrown upwards hits a roof and returns back to the ground. The upward movement is modelled by a function s=−t^2+3t+4 and the downward movement is modelled by s=−2t^2+t+7, where s is the distance (in metres) from the ground and t is the time in seconds.

Find the height of the roof from the ground.

Give your answer as a number without units.

The graph below shows the height of a projectile t seconds after it is launched. if acceleration due to gravity is -16 ft/s2, which equation models the height of the projectile correctly?

Complete the solution of the equation. find the value of y when x equals to 6 4x+y=20

Apinhole camera is made out of a light-tight box with a piece of film attached to one side and pinhole on the opposite side. the optimum diameter d(in millimeters) of the pinhole can be modeled by d=1.9[ (5.5 x 10^-4) l) ] ^1/2, where l is the length of the camera box (in millimeters). what is the optimum diameter for a pinhole camera if the camera box has a length of 10 centimeters