1. Objects with masses m 1 = 11.0 kg and m 2 = 7.0 kg are connected by a light s
ID: 1791105 • Letter: 1
Question
1. Objects with masses m1 = 11.0 kg and m2 = 7.0 kg are connected by a light string that passes over a frictionless pulley as in the figure below. If, when the system starts from rest, m2 falls 1.00 m in 1.49 s, determine the coefficient of kinetic friction between m1 and the table.
2. A car accelerates down a hill (see figure below), going from rest to 20.0 m/s in 6.20 s. A toy inside the car hangs by a string from the car's ceiling. The ball in the figure represents the toy, of mass 0.860 kg. The acceleration is such that the string remains perpendicular to the ceiling.
(a) Determine the angle .
_______ °
(b) Determine the tension in the string.
_______ N
Explanation / Answer
1. m1 = 11 kg
m2 = 7 kg
acceleration of the system = a
now, d = 1 m
t = 1.49 s
hence
d = 0.5at^2
a = 2/1.49^2 = 0.9008 m/s/s
now, from force balance
let tension in the string be T
m2g - T = m2a
T - k*m1*g = m1*a ( where k is coefficient of friction)
(m2 - k*m1) = (m1 + m2)a/g
k = 7/11 - (11 + 7)a/9.81*11 = 0.486
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