1.A small object is at rest on one edge of a horizontal table that is 1.0 m in l
ID: 1472082 • Letter: 1
Question
1.A small object is at rest on one edge of a horizontal table that is 1.0 m in length. The surface of the table is quite smooth, but friction cannot be ignored completely. The object is given a quick push to start it moving, it moves across the table, and it eventually falls off the other edge of the table after 2.0 s. Is it possible for this object to NOT have any wheels (meaning it is sliding instead of rolling)? Note that the kinetic friction coefficient between most all materials is at least 0.1. Show all calculations to prove your answer choice!
2. make toy racetracks that have “loop-the-loops” as shown in the figure below (open link). have the toy cars go completely around the loop without falling out due to gravity. They would like to be able to make several different sizes of the tracks and loops. So instead of giving you specific numbers for R and h and m, they need you to derive an expression that relates h and R so that the toy cars will always stay on the loop, even when allowed to roll down the slope from rest (don’t rely on any initial speed of the toy car at the top…). Basically, for a given loop radius, R, how high must the slope of the track be (h) to ensure the toy cars will go around the loop without falling off? You can ignore the small effects due to friction on the track and air resistance.
w/ #2. http://postimg.org/image/cmapzwhwb/4503ebbf/
Explanation / Answer
Length of the table, d=1m
F= mu* N
mu =Kinetic friction factor,
N=normal force m*g
F= ma=mu*m*g
a= mu*g
mumin= 0.1,
Min deceleration,
amin =.01*9.81 =.981
Now, as we know,
V0 =initial speed
d= X= Vo t + 1/2 at^2
1=2*Vo+(1/2)*(-.981)*4
1-1.962=Vo*2
Vo=-0.481.
It is not posible by sliding motion as if initial speed would be in negative than the object would fall off the edge.
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