Speed when a system is jerked into motion

AI Thread Summary
The discussion revolves around a physics problem involving two connected particles and their motion when released from rest. Participants are trying to determine the tension in the string, the acceleration of the particles, and the highest point reached by the 5 kg mass. There is confusion regarding the term "speed with which the system is jerked into motion," with some interpreting it as the initial speed, which is zero, while others question how to calculate it given the acceleration and time. The participants also discuss the implications of the inextensible string on the heights of the masses during their motion. Overall, clarity on the terminology and the calculations involved is needed to solve the problem effectively.
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Homework Statement


Two particles of masses 8 kg and 5 kg are connected to the two ends of a light inextensible string which passes over a fixed smooth pulley. Initially each of the two particles are held at a position which is 5 m above a horizontal ground. The objects are then released from rest. Assuming that the particles never reach the pulley, and also that the particles do not rebound when they strike the ground
(i) find the tension in the string and the acceleration of each particle
(ii) find the distance above the ground of the point H, the highest point reached by the 5 kg mass
(iii) find the speed with which the system is jerked into motion and the impulse experienced by the string during the jerk

Homework Equations


Kinematics and dynamics

The Attempt at a Solution


(i) I am able to do this

(ii) because the particles never reach the pulley, the highest point is 10 m, which is when the 8 kg-mass reaches the ground. Correct?

(iii) I do not understand this one. What is the meaning "speed with which the system is jerked into motion"? I interpreted it as the initial speed of the system and the answer should be zero? If not, maybe the speed when the particles start to move. But how to find it? I have acceleration and the initial speed is zero (because the particles are at rest and then released), but the speed depends on the time. What is the time that I should take to put to the equation of motion?

Thank you very much
 
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(ii) Both are initially 5m above ground. what would be height of one if other is moved to ground. keep in mind that string is inextensible.

(iii) impulse is change in momentum i.e. dP
but even i don't know what "speed with which the system is jerked into motion" means
 
cupid.callin said:
(ii) Both are initially 5m above ground. what would be height of one if other is moved to ground. keep in mind that string is inextensible.

10 m?
(iii) impulse is change in momentum i.e. dP
but even i don't know what "speed with which the system is jerked into motion" means


This question confused me. Can anyone please interpret waht the question means?

Thank you very much
 

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