Value of h=48t-16t^2 when t = 2 and t = 2.5.

The two questions are similar but I keep getting way different answers

A water rocket is launched upwards with an initial velocity of 28 ft/sec. Its height H in feet after t seconds is given by h=48t-16t^2. Determine the height of the rocket after 2.5 secs after it has been launched.

The second question is the same, but 2.0 secs after launch

Thanks so much guys

Re: help with 2 word problems - factoring

Quote:

Originally Posted by

**bashemgud** The two questions are similar but I keep getting way different answers

A water rocket is launched upwards with an initial velocity of 28 ft/sec. Its height H in feet after t seconds is given by h=48t-16t^2. Determine the height of the rocket after 2.5 secs after it has been launched.

The second question is the same, but 2.0 secs after launch

Thanks so much guys

Substitute t = 2.5 and t = 2 into h=48t-16t^2 and do the arithmetic.

Re: Value of h=48t-16t^2 when t = 2 and t = 2.5.

so 2.0 secs is 32feet and 2.5 is 20 feet?

for some reason it seems backwards to me.

Re: Value of h=48t-16t^2 when t = 2 and t = 2.5.

This is because after 1.5 seconds, the rocket is descending.

Re: Value of h=48t-16t^2 when t = 2 and t = 2.5.

Quote:

Originally Posted by

**bashemgud** so 2.0 secs is 32feet and 2.5 is 20 feet?

for some reason it seems backwards to me.

Your answers are correct but your discomfort with them is concerning. I suggest you review parabolas and their graphs.

Re: Value of h=48t-16t^2 when t = 2 and t = 2.5.