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

1 Answer
Oct 12, 2014

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 :)