A .5kg ball is dropped from a 30m high building is on the ground for 2ms then bounces up 20m. What avg force was exerted on the ball?
The law of conservation of energy
m•g•h1=m•v1²/2
v1=sqrt(2•g•h1)=sqrt(2•9.8•30) =24.3 m/s
m•v2²/2=m•g•h2
v2=sqrt(2•g•h2)=sqrt(2•9.8•20) =19.8 m/s
The law of conservation of linear momentum
p=m•v2-m• (-v1)=m(v2+v1)=FΔt
F= m(v2+v1)/ Δt=0.5(24.3+19.8)/0.002=44100 N