Physics, 07.10.2019 22:00 victoria1831

Aperson places a cup of coffee on the roof of her car while shedashes back into the house for a forgotten item. when she returnsto the car, she hops in and takes off with the coffee cup still onthe roof.
(a) if the coefficient of static frictionbetween the coffee cup and the roof of the car is 0.22, what is the maximum acceleration the car canhave without causing the cup to slide? ignore the effects of airresistance.
1 m/s2
(b) what is the smallest amount of time in which the person canaccelerate the car from rest to 13 m/s andstill keep the coffee cup on the roof?

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Answer from: lainnn974

(a) 2.2 m/s^2

Along the vertical direction, the acceleration of the cup is zero, therefore the equation of the forces is:

N-mg=0

where N is the normal reaction and (mg) is the weight of the cup, with m being its mass and g the acceleration of gravity. From this equation we get

N=mg (1)

Along the horizontal direction, the only force acting is the force of friction. The maximum force of friction acting on the cup is

$f_f = \mu N$

where $\mu=0.22$ is the coefficient of static friction between the cup and the roof of the car. The maximum acceleration that the car can substain withouth the cup sliding away corresponds to the maximum force of friction on the cup, so we can write:

$F =\mu N = ma_{max}$

And solving for $a_{max}$ and using eq.(1), we get:

$a_{max} = \mu g = (0.22)(9.8)=2.2 m/s^2$

(b) 5.9 s

To solve this part of the problem, we can use the following SUVAT equation:

v = u+at

where

v is the final velocity

u is the initial velocity

a is the maximum acceleration

t is the smallest amount of time

In this problem,

v = 13 m/s (final velocity of the car)

u = 0 (initial velocity)

a = 2.2 m/s^2

Solving for t,

$t=\frac{v-u}{a}=\frac{13}{2.2}=5.9 s$

Answer from: Quest

a, c, d, e are all applying about success strategies.

Answer from: Quest

An atom (ours, not carroll's) consists of a positively charged nucleus, surrounded by one or more negatively charged particles called electrons. the positive charges equal the negative charges, so the atom has no overall charge; it is electrically neutral. most of an atom's mass is in its nucleus; the mass of an electron is only 1/1836 the mass of the lightest nucleus, that of hydrogen. although the nucleus is heavy, it is quite small compared with the overall size of an atom. the radius of a typical atom is around 0.1 to 0.25 nanometres (nm), whereas the radius of a nucleus is about 10-6 nm. * if an atom were enlarged to the size of the earth, its nucleus would be only 200 feet in diameter and could easily rest inside a small football stadium.read more on -

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Aperson places a cup of coffee on the roof of her car while shedashes back into the house for a forg...