# Question #f48ee

##### 1 Answer

#### Answer:

#### Explanation:

The question is essentially asking for the **height** above ground level at which the object will find itself

As you know, an object's **gravitational potential energy**, *against gravity* to lift the object to that height.

The equation that allows you to calculate an object's gravitational potential energy looks like this

#color(blue)(ul(color(black)(U = m * g * h)))#

Here

#m# is the mass of the object#g# is the gravitational acceleration, usually given as#"9.81 ms"^(-2)# #h# is the height above ground

Now, in order to find the height above ground at which the object finds itself, you can use the equation

#color(blue)(ul(color(black)(h = v_0 * t - 1/2 * g * t^2)))#

Here

#v_0# is the initial velocity of the object#t# is the total time of flight

Plug in your values to find

#h = "15 m" color(red)(cancel(color(black)("s"^(-1)))) * 2 color(red)(cancel(color(black)("s"))) - 1/2 * "9.81 m" color(red)(cancel(color(black)("s"^(-2)))) * 2^2 color(red)(cancel(color(black)("s"^2)))#

#h = "10.38 m"#

So, the object is located **above ground**

#U = "1.5 kg" * "9.81 m s"^(-2) * "10.38 m" = color(darkgreen)(ul(color(black)("153 J")))#

I'll leave the answer rounded to three **sig figs**, but keep in mind that you only have one significant figure for the time of flight.