A rocket is launched straight up from the side of a cliff 40m high. If the initial velocity (v) is 30 m/sec and the height (H) is given by the formula = −16² + + ℎ, find the time at which the rocket will hit the ground. * plsss help again :>>
A. 2.78sec
B. -0.90sec
C. 3.1sec
D.-0.6sec

The time that the rocket will hit the ground is after 2.78 seconds.

Step-by-step explanation:

You know that the height (H) is given by the formula H= −16*t² + v*t+ h

A rocket is launched directly from the side of a 40 m high cliff and that the initial velocity is 30 m / sec. So this indicates that the value of v is 30 m / sec and h is the height of 40 m.  Replacing this value in the formula you get:

H= −16*t² + 30*t+ 40

You must find the moment when the rocket will hit the ground, that is, the moment when the height H is zero:

0= −16*t² + 30*t+ 40

To calculate the time t the expression is used:

Being the general quadratic equation ax² + bx + c = 0, in this case a=-16, b=30 and c= 40. Replacing:

Solving:

Then:

 or  

Solving for t1:

t1=-0.9

Solving for t2:

t2=2.78

Since the time cannot be negative, the time that the rocket will hit the ground is after 2.78 seconds.

darn right!

step-by-step explanation:

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