How far would a biker travel on the ground, if he fell off a motorbike travelling at 50 miles per hour?

Question

I am just going on averages here.

This is an experiment we did (not with a real person of course) and stupidly at the time no-one logged the details. So all I know is that he is travelling at 50mph on a runway, (no trees or walls or cliffs) Any help!?

Answer 1

He would initial travel through the air, and we'll assume he's unimpeded by air resistance. He's only got about 2 feet to fall, and gravity accelerates him downward at 32.2 ft/s^2. Using y = 0.5*g*t^2 ==> t = sqrt(2y/g) = sqrt(2*2/32.2) = 0.35 s. The distance in the direction of travel is (0.35 s)(50 mi/hr)(1 hr / 3600 s)(5280 ft/mi) = 26 ft. But he's still moving foward at 50 mph. Now, friction with the ground will slow him to a stop. Let's assume the coefficient of kinetic friction is 0.5; I figure it would be fairly high, with all the dust getting kicked up and the rocks and things. So the friction force against him is 200*0.5 = 100 lbf. That's half the force of gravity, so he'll decelerate at 16.1 ft/s^2, half the gravitational acceleration. The time this takes to stop him is t = v/a = (50 mi/hr)(1 hr / 3600 s)(5280 ft/mi)/(16.1 ft/s^2) = 4.6 s. The distance traveled is v_0*t + 0.5*a*t^2 = (50 mi/hr)(1 hr / 3600 s)(5280 ft/mi)(4.6 s) - 0.5(16.1 ft/s^2)(4.6 s)^2 = 171 ft. The total distance traveled is thus 26 + 171 = 196 ft (with rounding). This seems fairly high, and was based on a lot of assumptions. Perhaps air resistance would have a measurable effect, and maybe the coefficient of friction would actually be much greater than I guessed. If I double the friction, the result becomes 109 ft. If I double it again, it's 88 ft.

Answer 2

One thing is, what is the ground terrain like. Is he falling onto loose gravel, or black top, or a cement road, wet grass? All those things are going to affect how far the biker is going to slide. Wet grass, he is going to go further than dry. Even a wet road: black top or cement is going to make a difference. What is the biker wearing? That can make a difference too. In a leather suit is going to be different than jeans and shirt. And if the biker is in shorts and short sleeved tee-shirt, that is going to make a difference. I have seen lots of motorcycle accidents and they were all affected by the above conditions.

Answer 3

Don't know... last month a biker in my town fell off at about 50 mph and slid almost 20 feet before getting run over by a Honda Accord... parts of him continued for a few more feet but most of him stayed under the car...

All it takes is one small mistake....

Answer 4

If he hit a concrete wall, Zero Feet

Velocity = Distance minus drag or friction x Time
Distance = Velocity/Time

D V MPH T
0.833333333 50 0.016666667
4.166666667 50 0.083333333

Answer 5

That would depend on the coefficient of friction between his body and the ground and how he hit the ground (flat, rolling, etc.). Speaking of the ground, are we talking cement, asphalt, dirt?

Having no actual ability to calculate the problem, I'll just take a shot. I'll assume asphalt. Maybe... 75 feet?

Answer 6

depends on how many objects are in the path,also minutely on the resistance offered by the clothing and speed and direction of apparant wind,as well as weather conditions

Answer 7

Depends on the kind of ground.

Answer 8

What about off a cliff?

Answer 9

Depends if he hit a tree or not.

Answer 10

it depends. road, grass, up hill, down hill, dirt, a lot of factors go into this but its a thinker i give you that!