eli5: how does the driving stunt where they drive on a vertical wall in a circle work. Had to describe it like this as it contains a banned word.. but yeah.. can kinda understand bikes as bikes go fast and are light brrrr how does a +1 ton car go on the full vertical part and not fall off
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The minimum speed required to avoid falling in a loop does not depend upon the mass of the object. A heavier object will find it more difficult (need more energy) to accelerate to the required speed, but if it reaches that speed it doesn’t matter the weight (assuming the loop/cage can support the forces involved (which are dependent upon the mass).
The minimum required speed to avoid falling is a simple formula…
v >= sqrt(g*r)
g = gravitational acceleration (about 9.8 m/s)
r is the radius of the loop (the larger the loop the greater the required velocity)
The idea is that you need at least enough centripetal acceleration at the top of the loop to counter the pull of gravity.
The force due to gravity is mg. The force due to centripetal acceleration is F = mv^2/r.
So for a net force of zero, we just equate these two…
mg = mv^2/r
Since the mass (m) appears on both sides we can eliminate it by dividing both sides by m (we’re assuming our car is not massless). This leaves…
g = v^2/r
or…
v^2 = gr
so…
v = sqrt(gr) — no dependence upon mass, just gravitational acceleration and radius of loop.
Take a bucket. Fill it with water.
And then spin that bucket in an arc above your head. You will notice that the water, once at the right speed, doesn’t fall out of the bucket.
The water is propelled away from you, hits the bucket and then stays there.
That’s what is happening with your car.
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