A toy rocket is launched upward from ground level with an initial velocity of 42 meters per second. Its height is a function of time, given by h=-4.9^2+42t, where h represents the height in meters and t represents the time in seconds.

a. The maximum height reached by the rocket is?
b. The minimum height reached by the rocket is?

Question

A toy rocket is launched upward from ground level with an initial velocity of 42 meters per second. Its height is a function of time, given by h=-4.9^2+42t, where h represents the height in meters and t represents the time in seconds.

a. The maximum height reached by the rocket is?
b. The minimum height reached by the rocket is?

danjs · Answer

when the velocity equals zero

anonymous · Answer

i swear i just answered this question 
honest

danjs · Answer

^ happens all the time, should be an archive of all the questions with an easy search feature

danjs · Answer

Find 

$$\frac{ dh }{ dt }=0$$

that time t, is where the velocity is zero, use that in the h(t) given function to get the height at that time t.

anonymous · Answer

answered it without calc too, just using the vertex is all

danjs · Answer

right, it is a parabolic path, maximum height is at the vertex , if you want to do it that way too

anonymous · Answer

I really can't figure it out can you tell me the maximum? ill give you a medal

anonymous · Answer

plug in $\frac{30}{7}$ in to the equation for $t$ or else cheat, i will show you how

anonymous · Answer

scroll down to where it says "maximum" you will see it is 90 http://www.wolframalpha.com/input/?i=-4.9x^2%2B42x

anonymous · Answer

thanks