(A) The speed of the pendulum when it reaches the bottom is 3.83 m/s.
(B) The speed of the pendulum when it reaches the bottom after losing 18% of its energy is 3.47 m/s.
(C) The height reached by the pendulum after losing another 7% of its energy is 0.57 m.
(D) When the pendulum stops swinging, it has used all its energy to overcome frictional force of air.
Apply the principle of conservation of energy;
K.E = P.E
¹/₂mv² = mgh
v² = 2gh
v = √2gh
v = √(2 x 9.8 x 0.75)
v = 3.83 m/s
K.E = (100 - 18)P.E
¹/₂mv² = 0.82mgh
V = √(0.82 x 2gh)
v = √(0.82 x 2 x 9.8 x 0.75)
v = 3.47 m/s
K.E = 0.5(1)(3.47)² = 6.02 J
When it losses 7% = 6.02 - (0.07 x 6.02) = 5.598 J
Height reached:
mgh = 5.598
h = 5.598/mg
h = 5.598/(1 x 9.8)
h = 0.57 m
When the pendulum stops swinging, it has used all its energy to overcome frictional force of air.
Thus, the speed of the pendulum when it reaches the bottom is 3.83 m/s.
The speed of the pendulum when it reaches the bottom after losing 18% of its energy is 3.47 m/s.
The height reached by the pendulum after losing another 7% of its energy is 0.57 m.
Learn more about speed of pendulum here: https://brainly.com/question/13655641
#SPJ1
