Question

A 4 kg hammer is lifted up to 10 m in height and then falls. What are potential and kinetic energies of the hammer at a point 4 m above the ground?

Answer 1

The potential and kinetic energies of the hammer at a point 4 m above the ground  are: 156.8 J and 235.2 J.

m = 4 Kg

hmax = 10 m

Ek=?

Ep=?

 h = 4m

 

 hmax = Vo²/2g

  Vo= √2*g*hmax = √2*9.8m/s2*10m = 14 m/s2

   Vf² = Vo²-2*g*h

   Vf= √(14m/s)²-2*9.8m/s2*4 m

   Vf = 10.84 m/s

   Ep = m*g*h

   Ep = 4Kg* 9.8 m/seg2 * 4 m

   Ep = 156.8 J

   

   Ek = m*Vf²/2

  Ek = 4Kg * ( 10.84m/s )²/2

  Ek = 235.2 J