A mass m is thrown horizontally at 5.00 m/s off a 20.0m high cliff. find its speed at impact

a)using projectile analysis (20.4m/s)
b) using energy analysis

1 answer

Vertical component of velocity on impact
= sqrt(2*gh)
=sqrt(2*9.8*20)
=19.8 m/s
horizontal component
=5 m/s
resultant velocity
=sqrt(5²+19.8²)
=20.42 m/s

By energy considerations:
Total kinetic and potential energies at the bottom of the cliff
(1/2)mV²= (1/2)m(5)² + mg(20)
V=sqrt(5²+2g(20))
=20.42 m/s