Friday

December 19, 2014

December 19, 2014

Posted by **Billie** on Tuesday, September 19, 2006 at 6:06pm.

I can't figure out which equation to ues. but I know that v=12m/s, d=80m and t=?

Since the object is not acclerating I 'think' you would just use

s=(1/2)g*t^2 where s=80m

The object would have constant velocity until it's dropped. Then it's under the influence of gravity completely.

Check my reasoning on this.

I'm now quite sure I gave the wrong answer to this question.

The ballon's velocity is 12m/s upward and it's 80 m above the ground. A package is dropped over the side, and we want to know how long does it take for the package to hit the ground.

We should use

(1) s=(-1/2)g*t^2 + v_o*t + x_o and

(2) v=-g*t + v_o

Here x_o = 80m and v_o=12m/s. First we should determine how long it takes for the object to stop moving upward. Using (2) we find

0=-9.8m/s^2*t + 12m/s so t=12/9.8s=1.22s. using this in (1) we get

s=(-1/2)9.8m/s^2*(1.22s)^2+12m/s*1.22s + 80 = something you can do.

This is the height from which the stone in under the influence of gravity completely

Use that height and solve for t using

s=(1/2)g*t^2

Add that time to the 1.22s it needed going up to answer your question.

**Answer this Question**

**Related Questions**

physics - A hot-air balloon is ascending at the rate of 11 m/s and is 51 m above...

Physics - A hot-air balloon is ascending at the rate of 13 m/s and is 62 m above...

physics - A hot-air balloon is ascending at the rate of 13 m/s and is 73 m above...

physics - A hot air balloon is ascending at the rate of 13 m/s and is 75 m above...

AP Physics - A hot air balloon is ascending at the rate of 13 m/s and is 75 m ...

physics - A package in an airplane moving horizontally at 150m/s is dropped when...

Physics - A helicopter is ascending vertically with a speed of 9.00 m/s. At a ...

physics - a helicopter is ascending vertically with a speed of 5.20 m/s. at a ...

physics - a helicopter is ascending vertically with a speed of 5.20 m/s. at a ...

Physics - A helicopter is ascending vertically with a speed of 4.50 m/s. At a ...