A pendulum of length 1 m attains a height of 0.5 m above the surface of a table on which it is placed. How fast will the bob move at the lowest point above the surface of the table (say h = 0)?
Answers
Answer:
Length of the pendulum, l=1.5m
Mass of the bob =m
Energy dissipated =5%
According to the law of conservation of energy, the total energy of the system remains constant.
At the horizontal position A:
Potential energy of the bob, E
P
=mgl
Kinetic energy of the bob, E
K
=0
Total energy =mgl ------ (i)
At the lowermost point (mean position) B:
Potential energy of the bob, E
P
=0
Kinetic energy of the bob, E
K
=
2
1
mv
2
Total energy E
x
=
2
1
mv
2
....(ii)
As the bob moves from the horizontal position to the lowermost point, 5% of its energy gets dissipated.
The total energy at the lowermost point is equal to 95% of the total energy at the horizontal point, i.e.,
2
1
mv
2
=
100
95
mgl
v=(
100
2×95×1.5×9.8
)
1/2
v=5.28m/s
https://courses.lumenlearning.com/physics/chapter/16-4-the-simple-pendulum/
