Two blocks A and B have a weight of 10 lb and 6 lb , respectively. They are rest
ID: 1481897 • Letter: T
Question
Two blocks A and B have a weight of 10 lb and 6 lb , respectively. They are resting on the incline for which the coefficients of static friction are ?A = 0.14 and ?B= 0.26. Determine the incline angle ? for which both blocks begin to slide. Also find the required stretch or compression in the connecting spring for this to occur. The spring has a stiffness of k = 2.1 lb/ft
Part A
Determine the incline angle ? for which both blocks begin to slide.
Express your answer to three significant figures and include the appropriate units.
Part B
Determine the change of the length of the spring. Assume this change to be positive if the spring is stretched and negative if the spring is compressed.
Express your answer to three significant figures and include the appropriate units.
Explanation / Answer
force equation of block A
mAg * sin(theta) - A * mg * cos(theta) + kx = 0
10 * 32.174 * sin(theta) - 10 * 32.174 * cos(theta) + 2.1 * x = 0
force equation of block B
mBg * sin(theta) - B * mg * cos(theta) - kx = 0
6 * 32.174 * sin(theta) - 0.26 * 6 * 32.174 * cos(theta) - 2.1 * x = 0
on solving we'll get
change in length of spring x = 34.462 ft
theta = 35.85 degree