an object dropped from a height of 210ft will fall according to the equation h(t) =210-16t^2. how long will it take the object to reach the ground

Step-by-step explanation:

By saying reach the ground, it means the altitude will be zero, so the equation will be: 210 - 16t^2 = 0

210 = 16t^2, t =  

since the airplane is moving with constant speed then the distance travelled can be calculated by x=u*t

in km/h would be:

x=640*3.5=2.240 km

in m/s would be:

u=640 km/h= 640.000 m/h =640.000/ 3600 m/s =177.8 m/s

t= 3.5 h= 3.5 * 3600 s=12.600 s

then x=u*t= 177.8*12.600= 2.240.280 m

answer: i wpould go with c

step-by-step explanation: