# Horse power to g-force

1. Jun 27, 2010

### milton3

This question is for background information on a start up technology.

Starting with the tetherball analogy: Assuming the force would be applied to spinning the base of the tetherball pole what amount of horse power is needed to get the tetherball up to a speed of 36 miles per hour with these properties; tetherball poll (2 kilograms), string (1 meter) and ball (1.9 kilograms)?

At constant speed what is the max g-force?

If the process was reversed, 36 mph to zero, what would be the max g-force?

2. Jun 27, 2010

### rcgldr

If there's no friction or drag, then any (non-zero) amount of power will eventually get the ball up to speed.

3. Jun 27, 2010

### litup

You should at least keep the units the same, 36 mph is 57.6 Kilometers/hour.
The other problem is you did not specify a time frame. Horsepower and such in terms of lifting power is defined as the ability to move or lift straight up 555 pounds (252.27 kg) one foot (304 mm, 30.4 cm) in one second. So if you could apply one hp to 555 pounds in space as an acceleration it would give 1/32 of a G, so 32 hp would accelerate 555 pounds in space at one G.

You need to be more specific about your units and such. Try it again.

4. Jun 28, 2010

### jack action

Whenever you are talking power or acceleration, you need to set a time restriction. Power is the amount of energy spent in a given time and acceleration is the amount of velocity variation in a given time.

To get a mass m to go from 0 to velocity v, you need an amount of energy equal to http://en.wikipedia.org/wiki/Kinetic_energy#Newtonian_kinetic_energy". If you divide this amount of energy by the the time taken to reach v, you will get the average horsepower needed.

Technically, http://en.wikipedia.org/wiki/G-force" [Broken] principle.

Here you have the speed difference, but you don't specified the time, so we cannot determine the acceleration (or deceleration, in this case).

Last edited by a moderator: May 4, 2017