Question

What height will a dart achieve 7 seconds after being blown straight up at 50 m/s?

Answer 1

It is 100 m

Since this is motion in only one dimension, it is a relatively simple problem to solve.

As we're given time, acceleration and initial velocity, we can use our time dependent equation of kinematics, which is:

`Deltay=v_ot+1/2at^2`

Now let's list out our given values:

`t = 7` seconds
`v_o = 50`m/s
`a = -9.8`m/`s^2` (Gravity acting downwards)

So now all we need to do is plug in and solve:

`Deltay` = 50(7) + `1/2`(-9.8)(`7^2`)

`Deltay =`109.9 m#

However, we would round this down to 100 because of the 1 significant digit in our given information (if you have 50. and 7.0, you would round it to 2 sig figs, which would be 110).

Hope that helped :)