Question

A worker's hammer is accidentally dropped from the 20th floor of a building under construction. With what velocity does it strike the pavement 304 ft below, and what time t is required?

Answer 1

Answer:

Final Velocity (Vf)= 139.864 ft/s

Time (t)= 4,34 s

Explanation:

This is a free fall problem, to solve it we will apply free  fall concepts:

In a free fall the acceletarion is gravity (g) = 9,81 m/s2, if we convert it to ft/s^2 = g= 32.174 ft/s^2

• Final velocity is Vf= Vo+ g*t[tex]Vf^{2} = Vo^{2} +2*g*h

where h is height (304 ft in this case).

Vo =0 since the hammer wasn't moving when it stared to fall

Then Vf^2= 0 + 2* 32.174 ft/s^2 *304 ft

          Vf^2= 19,561.8224  ft^2/s^2

          Vf=[sqrt{19561.8224 ft^2/s^2}

          Vf=139.864 ft/s

Time t= (Vf-Vo)/g => (139.864 ft/s-0)/32.174 ft/s^2 = 4.34 sec

Good luck!