- #1
Yam
- 32
- 1
Homework Statement
A car traveling at 20 m/s stops in a distance of 60 m. Assume that the deceleration is constant. The coefficients of static and kinetic friction between a passenger and the seat are Us and Uk respectively. You may assume that the passenger is not in contact with anything else. Which of the following statements below is true?
a) The passenger will slip off the seat if he is light and remain on the seat if he is heavy.
b) The passenger will not slip off the seat regardless of the values of Us and Uk .
c) The passenger will slip off the seat regardless of the values of Us and Uk .
d) The passenger will not slip off the seat if Us> 0.4
e) The passenger will slip off the seat if Uk<0.3
Homework Equations
Kinematics : v^2 = u^2 +2as
Newton's second Law: F=ma
Force of Friction: Us*Normal Force
The Attempt at a Solution
a) The passenger will slip off the seat if he is light and remain on the seat if he is heavy.
The statement is too ambiguous.
b) The passenger will not slip off the seat regardless of the values of Us and Uk .
As long as F>UsN, the passenger will slip
c) The passenger will slip off the seat regardless of the values of Us and Uk .
As long as F>UsN, the passenger will slip
d) The passenger will not slip off the seat if Us> 0.4
e) The passenger will slip off the seat if Uk<0.3
I will attempt to find out the minimum Us that is required so that the passenger will not slip.
0 = 20^2 + (2)(a)(s)
a = 10/3
(m*g*Us)=ma
Us = 10/3g =0.34, which doesn't fit into any option above.
May i know if i made any errors in concept or calculation