The systems shown below are in equilibrium (with m = 4.80 kg and = 32.0°). If th
ID: 1427095 • Letter: T
Question
The systems shown below are in equilibrium (with m = 4.80 kg and = 32.0°). If the spring scales are calibrated in newtons, what do they read? Ignore the masses of the pulleys and strings and assume the pulleys and the incline are frictionless.
A crate of mass m = 31 kg rides on the bed of a truck attached by a cord to the back of the cab as in the figure. The cord can withstand a maximum tension of 76 N before breaking. Neglecting friction between the crate and truck bed, find the maximum acceleration the truck can have before the cord breaks.
m/s2
Explanation / Answer
a)
reading of spring scale = mg + mg = 2*mg = 2*4.8*9.8 = 94.08 N
b)
reading of spring scale = mg = 4.8*9.8 = 47.04 N
c)
reading of spring scale = mg + mg = 2*mg = 2*4.8*9.8 = 94.08 N
d)
reading of spring scale = mgsin(theta) = 4.8*9.8*sin32 = 24.93 N
2)
The cord can withstand a maximum tension = 76 N
the maximum acceleration the truck can have before the cord breaks = T/m = 76/31 = 2.45 m/s^2