A pendulum swings back and forth up to a maximum height of 1.52 m. Neglecting friction, what is the speed of the pendulum at the lowest position.
a) 2.7 m/s
b) 3.9 m/s
c) 5.5 m/s
d) 30. m/s
I thought the answer would be 0 m/s because it wouldn't move at the lowest position? However, that's not an answer choice. What is the proper formula to use?
2 answers
C. 5.5 m/s
The potential energy at the top is equal to the kinetic energy at the bottom, therefore mgh=.5mv^2. The masses do not matter sense they are equal to each other, so they may be canceled out. You know that the acceleration of gravity is 9.8, so to find the left side--the potential energy-- you do 9.8*1.52. which gives you 14.896. Then you solve for v by isolating the variable. so you multiply by 2 on both sides, then find the square root on both sides. Giving the answer 5.45... or the actual answer C) 5.5 m/s
1 answer