We have the equation of motion [tex]s = ut + \frac{1}{2} at^2[/tex], where s is the displacement, a is the acceleration, u is the initial velocity and t is the time taken.
Here s = 300 m, u = 0 m/s, a = 9.81 [tex]m/s^2[/tex]
Substituting
[tex]300 = 0*t+\frac{1}{2} *9.8*t^2\\ \\ 4.9t^2 = 300\\ \\ t =7.82 seconds[/tex]
Now we have v = u+at, where v is the final velocity
Here u = 0 m/s, a= 9.81 [tex]m/s^2[/tex] and t = 7.82 seconds
Substituting
v = 0+9.8*7.82 = 76.68 m/s
The speed with which the penny strikes the ground = 76.68 m/s.
