20. A 15.9kg rock is dropped from a height of 113m. Calculate its potential energy. What is the rock'skinetic energy right before it hits the ground? What is the rock's velocity right before it hits the ground?

Relax

Respuesta :

Kinetic energy = 1/2 * m * v^2

Potential energy = m*g*h

m = 15.9 kg

h= 113 m

Potential energy = 15.9 kg * 9.8 N * 113 m = 17,607.66 J

Kinetic energy right before it hits the ground

PE = KE

mgh = 1/2 m v^2

Masses cancel out

gh = 1/2v^2

9.8 N * 113m = 1/2 v^2

Solve for v

1,107.4 Nm = 1/2 v^2

1,107.4 Nm / (1/2) = v^2

2,214.8 Nm = v^2

√2,214 = v

47.06 m/s = V

Kinetic energy : 1/2 * m * v^2 = 1/2 * 15.9 * 47.06^2 = 17,606.41 J