In: Physics
Calculate the final speed of an object if its initial speed is 10 m / s. The object has a mass of 5 kg. Initially it has a height of 20 meters, and it goes down to a height of 15 m. There are no dissipative forces on the object.
By work-energy theorem, change in potential energy
U = change in kinetic energy
K
change in potential energy
U = m
g
h
where m is mass, g is acceleration due to gravity and h is height difference between final position and
initial position
change in kinetic energy
K = (1/2)
m
(
vf2 - vi2 )
where vf is final speed and vi is initial speed
mg
h
= (1/2)
m
( vf2 - vi2 )
or ( vf2
- vi2 ) = ( 2
g
h ) = ( 2
9.8
5 ) = 98 m2s-2
vf2 = vi2 + 98 = 100 + 98 = 198
hence final speed vf =
= 14.07 m/s