Can you experience g-force without acceleration?

Submitted by tenminutes101010 t3_11bohwp in askscience

I was browsing this website that sells motion simulator rides and came across this ride called Giant Rider. On the website, it claims the ride can produce "1.5G acceleration". This confuses me, because it appears the ride is on fixed axises. When I think of acceleration, I think of a gradual speeding up like a car. Acceleration in this context doesn't seem possible to me since it is contained. Maybe the website is lying, or I'm just dumb. Any help is appreciated.

https://www.bhmvending.com/Amusements/Simuline/giant_rider.html

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valcatosi t1_j9zgvru wrote

You're not dumb. The only thing you're missing is that acceleration is a change in velocity, not a change in speed.

What does that mean? Picture a car driving down the freeway. The speed is what you see on the dashboard, and the velocity is that plus the direction you're going. Now picture driving around a curve in the freeway. The speed stayed the same, but the velocity changed because you changed direction, and while you were on the curve you felt a sideways force. That force is the result of the acceleration that changed the car's velocity but not its speed.

If that makes sense, now picture a car driving around a circular track. The speed stays the same all the time, but the velocity always changes because the car's direction is always changing. The result is that even though the car isn't speeding up or slowing down, you feel a force - that's acceleration!

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Mdork_universe t1_ja104qh wrote

Excellent illustration! I used this to demonstrate the constant acceleration of planets in orbit around the sun.

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risk-vs-reward t1_j9zf2fn wrote

On the ride soarin at Disney you are essentially seated on a big swing. As you are “flying” they tilt you back and you get the feeling of acceleration without any motion other than slight rotation backwards (5 degrees?). I think shifting your weight from the seat to the seat back makes you feel like you are experiencing g force.

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BloodshotPizzaBox t1_j9z5sjz wrote

The ride appears to shake its car around using hydraulic arms. So it's speeding up and slowing down all the time, changing the speed and direction (remember that velocity and therefore acceleration includes both) of the car's motion.

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18121812 t1_j9zwyka wrote

>When I think of acceleration, I think of a gradual speeding up like a car.

This is I think the key point of confusion. Acceleration can happen if very short distances and times, and in fact some of the largest acceleration values happen in extremely short distances and times.

For a basic demonstration, take a penny and hold it a meter over the floor, then let it go. It falls to the floor, and stops. (I'm going to ignore air resistance here)

When you let go, it immediately accelerates downwards at 9.8m/s^(2), or 1G. This continues until it hits the floor. It will be traveling downwards at a speed of about 4.4m/s after traveling one meter.

When it hits the floor, it decelerates, or more accurately, it is accelerating upwards. Now, how much it accelerates is going to depend on what your floor is made of, and how long it takes for it to come to a stop. Lets say in takes 0.1s to come to a stop, from initial contact.

For your penny to go from 4.4m/s to 0m/s in 0.1 second is actually a pretty big acceleration. 44m/s^(2), or about 4.5Gs.

If you somehow had a magic floor that could get that penny to stop in .001s, that penny would experience 450Gs!

Another example of extreme acceleration in a short space and time would be a bullet fired out of a gun. Initially, the bullet has a velocity of zero. When the gun is fired, the bullet experiences a very large acceleration, until it exits the barrel of the gun.

In short, you can get some really big Gs in a small space and time. This ride is moving around in a small space, and you can easily get 1.5gs in that space.

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FellowConspirator t1_j9zujg3 wrote

You are currently accelerating at 1g towards the Earth’s center of mass. The ground obviously prevents your fall, but you feel the acceleration as your weight.

The ‘g’ in 1.5g refers to acceleration of Earth’s gravity at the Earth’s surface, 9.8 m/s/s. Obviously, if the ride moves you it accelerates you, but slightly less obvious is that changing your direction (like swinging you in a circle, instead of allowing you to follow a straight line), also accelerates you. Consider the “Turkish Twist” ride where you stand in a large cylinder that spins. You experience a force that holds you against the wall. If you were on the outside, the spinning would throw you off in a straight line tangent to the cylinder. Inside, however, the wall is restraining you, pushing you onto the circular trajectory, accelerating towards the center of the circle at a rate proportional to the rotational velocity of the cylinder (you are experiencing acceleration even if the cylinder is rotating at a constant velocity). You are accelerating because your velocity (speed and direction of movement) are changing.

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Ketanovas t1_ja2gz6p wrote

Actually, we are currently accelerating Away from Earth's center of mass.

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Coomb t1_j9zs84p wrote

The limited travel of the hydraulics, pneumatics, or other actuators driving the ride cab means that the ride cannot provide anything other than 1g, normal gravity, indefinitely. However, that does not mean that the ride cannot provide higher or lower than normal gravity for relatively brief periods of time. All it needs to do is be able to drive the cab with enough force to exceed its weight.

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xratedcheese t1_ja2jlru wrote

Their claim:

"Giant Rider is capable of punching out 1.5G acceleration while the competition can only deliver 0.5G acceleration! "

That "punching out" was certainly carefully chosen. For a very brief period (fraction of a second?) they could jerk the whole cabin to give you the feeling of actual acceleration for that brief time, but absolutely not the feeling of sustained acceleration unless they are suspending the cabins and whirling them up to speed like amusement park swings.

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kdeff t1_ja6ogoc wrote

Vibration is what they are referring to, so +1.5g followed shortly after by an (eg.) -1.5g, and no net position change.

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