In: Physics
Calculate the maximum acceleration of a car with four wheel drive that is heading up a 8° slope (one that makes an angle of 8° with the horizontal) under the following road conditions. Assume that the static coefficient of friction is involved--that is, the tires are not allowed to slip during the acceleration.
(a) on dry concrete
________m/s2
(b) on wet concrete
_________ m/s2
(c) on ice, assuming that µs = 0.100, the same as for
shoes on ice
_________m/s2
coefficient of friction
dry concrete
on wet concrete
on ice
where:
static friction force.
Normal
force
car
weight
horizontal component of weight
vertical component of the weight
Applying Newton's second law in the x axis
but the sum of the forces on the horizontal axis is equal to
combining equations
remember and
now
is necessary to obtain expression N
not accelerate vertically
but also
combining
replacing
expression of N
substituting in
is obtained
simplifying m
organizing
if
acceleration of gravity
the equation is evaluated for each coefficient of friction
(a) on dry concrete
evaluated numerically
(b) on wet concrete
evaluated numerically
(c) on ice
evaluated numerically
the negative indicates that the car can not speed upward