The three flat blocks as shown in the figure are positioned on the 37º incline and a force P parallel to the inclined plane is applied to the middle block. The upper block is prevented from moving by a wire which attaches it to the fixed support. The masses of three blocks in kg and coefficient of static friction for each of the three pairs of contact surfaces are shown in the figure. Determine the maximum value which force P may have before slipping take place anywhere. (g = 10 m/s 2 )
Text Solution
Verified by ExpertsCHECK THE SOLUTION.
f ABmax = 0.3 × 30g cos37°
f ABmax = 0.3 × 30g cos37° = 72 N
f BCmax = 0.4 × 80g cos37° = 256 N
f Cmax = 0.5 × 120g cos37°= 480 N
when block ‘B’ is pulled two cases are possible
(1) B & C both moves together and there is just slipping at A & B contact and at C and wedge contact
(2) A & C remains stationary only ‘B’ tends to move downwards.
Taking case (1) Let B & C moves together and there is just slipping between A & B and between wedge
and C
⇒ P + 40 g sin 37° + 50 g sin 37° – 72 – 480 = 0 ⇒ P = 12 N
checking friction between B & C
f BC + 40 g sin 37° – 480 = 0
f BC = 240
which is within limit so case is correct.
so, max. force for which there will be no slipping P max = 12 N the at this force both B & C tends to move
together.
Prepare Smarter with CGP Edu
Get practice questions, solutions, and test series in one place.
Write a Review
Share your experience with this question and solution.
Commentary
Send your comment, doubt, correction, or feedback to admin.
Similar Questions
Explore conceptually related problems