# Regarding Friction/Normal force at 90(d) angle

#### PureSin

1. The problem statement, all variables and given/known data
I will try to explain it this way:
A truck hits a person, the person now is stuck on the trucks front.
Forces working on the person are Gravity and the force that the truck is applying.
The coefficient of the friction is $$\mu$$.

What should be the truck's acceleration in order for the person to stay "stuck" on its front.

2. The attempt at a solution
$$\Sigma$$F$$\hat{y}$$ = -mg+$$\mu$$*N
From what I understand we need $$\Sigma$$=0. I have never dealt with a problem in which the surface is placed at a 90 degrees angle. Could you guys please provide a solution/hint for what N is.

Thank you. :)

Last edited:

#### CarlRozario

N = m*a...
.
m = mass of the person
a = acceleration of the truck...
.
On a X-Y system...
If the truck is approaching along the x axis from right to left...
Now since you're in a non inertial frame...
The pseudo force acting is similar to what gravity would be if this all were friction calculated between an object and a leveled ground...
.
I'm curious... Are you planning to kill someone...
()

#### PureSin

Well thanks, I got it now.

Ask my Classical Mechanics professor, I'm starting to suspect that he has killing tendencies.

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