Question

A hard rubber ball on a string is being used as a pendulum. When you first look at the pendulum, the ball is being held to one side with the string fully extended. Suddenly, the ball is released from rest and allowed to swing back and forth. For the first three or four swings, the ball almost reaches the height from which it was released. However, after a long time has passed, the ball finally comes to rest, hanging straight down. (a) If the ball has a mass of 6.5 kg and is released from a height of 76 cm above its final resting height, find the amount of additional thermal energy that now exists in the air, the ball, the string, and the pivot of the pendulum. Give your answer in joules. (No Response) J (b) Answer the same question in kilocalories rather than joules.

Answer 1

a) Q = 48.42 J, b) Q = 1,157 10⁻² Kcal

Step-by-step explanation:

a) In this exercise we fear an initial energy

starting point. Higher

Em₀ = U = m g h

let's calculate

Em₀ = 6.5 9.8 0.76

Em₀ = 48.42 J

This energy is transformed by non-conservative forces into heat, they indicate that in air, as energy is not lost and there is no work since the displacement is zero

Em₀ = Q

Q = 48.42 J

b) reduce to kc

Q = 48.42 J (kc / 4184 J)

Q = 1,157 10⁻² Kcal