# HNC Dynamics help please -- Hoist cable looped over a winding drum

• TQGuru
In summary, the question is asking for various values related to a system involving a winding drum, a loaded hoist, and a cable. The moment of inertia and winding radius are provided, along with the mass of the hoist and the rate of acceleration. The frictional resistance is also given as a torque value. The tension in the cable, angular acceleration, and accelerating torque at the winding drum shaft are all determined using the given values. However, the total driving torque required at the winding drum shaft to produce the motion of the system is not explicitly stated in the conversation. Additionally, the question also asks for the maximum velocity of the hoist, but the calculation for this is not provided as there is no specific time given. Formulas
TQGuru
Hi guys I am looking for help with some formulas, its for hnc mech eng, the question is as follows a winding drum with moment of inertia 24 kg m2 and a winding radius of 0.6m is used to accelerate a loaded hoist with mass of 850kg at a rate of 0.8ms by means of a cable, frictional resistance can be considered as a torque of 88 Nm
determine
1- the tension required in the cable
3- Accelerating torque in Nm at the winding drum shaft required to accelerate the system
4- The total driving torque in Nm required at the winding drum shaft to produce the required motion of the whole system
I got 1 as 90,185N
3- 5411Nm
4 is 5531Nm but I am not sure how to derive at this answer
The question then goes on to velocity time diagram like questions and asking for sketches
the hoist covers a distance of 20m accelerating at 0.8ms from rest to a max speed then decelerates at the same rate, i.e for 10m constant acceleration
the part of the question I am struggling with is where it asks for the maximum velocity of the hoist, this is 4ms but I am beat for knowing the calculation as I don't have an specific time, Could anyone help me with the formula required to achieve the answer of 4ms?

Many thanks!

TQGuru said:
Hi guys I am looking for help with some formulas, its for hnc mech eng, the question is as follows a winding drum with moment of inertia 24 kg m2 and a winding radius of 0.6m is used to accelerate a loaded hoist with mass of 850kg at a rate of 0.8ms by means of a cable, frictional resistance can be considered as a torque of 88 Nm
determine
1- the tension required in the cable
3- Accelerating torque in Nm at the winding drum shaft required to accelerate the system
4- The total driving torque in Nm required at the winding drum shaft to produce the required motion of the whole system
I got 1 as 90,185N
3- 5411Nm
4 is 5531Nm but I am not sure how to derive at this answer
The question then goes on to velocity time diagram like questions and asking for sketches
the hoist covers a distance of 20m accelerating at 0.8ms from rest to a max speed then decelerates at the same rate, i.e for 10m constant acceleration
the part of the question I am struggling with is where it asks for the maximum velocity of the hoist, this is 4ms but I am beat for knowing the calculation as I don't have an specific time, Could anyone help me with the formula required to achieve the answer of 4ms?

Many thanks!

Welcome to the PF.

First off, you should be a bit more careful typing out the units. You seem to be using ms as a unit of velocity, but hopefully you mean m/s. Similarly what are the units of linear acceleration? What are the units for angular acceleration?

What is the equation that relates Force, mass and acceleration? What is the equation that relates Torque, Moment of Inertia and Angular Acceleration?

Can you show us your calculations for parts 1, 2 and 3? :-)

## 1. What is HNC Dynamics?

HNC Dynamics is a branch of engineering that focuses on the study and analysis of motion and forces in mechanical systems. It involves the use of mathematical equations and computational methods to understand the behavior of physical systems.

## 2. What is a hoist cable?

A hoist cable is a strong and flexible rope or wire that is used to lift or lower heavy objects. It is typically made of steel and can be wound around a drum or pulley system to provide mechanical advantage.

## 3. How does a hoist cable loop over a winding drum?

A hoist cable is typically attached to a load and passed over a winding drum. The cable is wrapped around the drum in a helical pattern, with each layer of cable tightly packed next to the previous one. This allows the cable to support the load and provide a mechanical advantage for lifting.

## 4. What is the purpose of a winding drum in hoist cables?

The winding drum in a hoist cable system serves as a mechanical device that allows the cable to be wrapped and unwrapped in a controlled manner. This helps to regulate the speed and direction of the load being lifted or lowered.

## 5. How can HNC Dynamics help with hoist cable design?

HNC Dynamics can be used to analyze and optimize the design of hoist cable systems. This includes determining the appropriate cable material, diameter, and length, as well as calculating the forces and stresses involved in lifting and lowering a load. This can help ensure the safety and efficiency of the hoist system.

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