• February 4th 2009, 04:49 PM
Soul to soul
A spaceship approaching touchdown on a distant planet has height h, in meters, at time t, in seconds, given by h=25t^2-100t+100. When does the spaceship land on the surface? With what speed does it land(assuming it descends vertically)?

Thanks
• February 4th 2009, 05:25 PM
skeeter
Quote:

Originally Posted by Soul to soul
A spaceship approaching touchdown on a distant planet has height h, in meters, at time t, in seconds, given by h=25t^2-100t+100. When does the spaceship land on the surface? With what speed does it land(assuming it descends vertically)?

Thanks

When does the spaceship land on the surface?

set h = 0 and solve for t.

With what speed does it land(assuming it descends vertically)?

$v(t) = \frac{dh}{dt}$

evaluate $\frac{dh}{dt}$ at the time that it lands.