Plase easy physics in two or more complete sentences, explain how to find the time it takes for a rocket following the path of the parametric equations, x = 3t^2 and y = -9t + 18, to hit the ground.

At 2 seconds the rocket will hit the ground

Explanation:

The rocket touches the ground when the altitude is 0, so, we must use the parametric equation of the altitude, that is why we will use the equation:

y = -9t+18.

Then we are going to search when the altitude or y is equal to 0 replacing the y for 0 as following:

0 = -9t+18

Now we move the expression -9t to the other side of the equality.

9t = 18

And then we move de 9 to divide on the other side of the equality.

t = 18/9

we solve the division and get:

t= 2

Our result is that the rocket touches the ground at t = 2, that is mean at 2.  seconds.

when a device is used in a circuit in which the voltage is 81 v, the current flowing through the device is 3 a. what is the resistance of the device?

a. 27 ω

b. 40.5 a

c. 243 ω

d. 243 a

the correct answer is a. 27

the maxium height is 34m/s