Paragraph for Questions 3 and 4: A 3 kg block is placed on a 4 kg block which is placed on a rough floor as shown in figure. (Between the blocks μ = 0.4, between the lower block and floor μ = 0.1, F = 28 N on the 4 kg block.)
Find acceleration $($ in $m / s^{2})$ of 3 kg block.

Question

Paragraph for Questions 3 and 4: A 3 kg block is placed on a 4 kg block which is placed on a rough floor as shown in figure. (Between the blocks μ = 0.4, between the lower block and floor μ = 0.1, F = 28 N on the 4 kg block.)

Find acceleration $($ in $m / s^{2})$ of 3 kg block.

TestHub · Accepted Answer

Limiting friction from the floor: f f l oor ​ = 0.1 × ( 3 + 4 ) × 10 = 7 N < 28 N , so the system moves. Assuming both blocks move together: a = 3 + 4 28 − 7 ​ = 3 m/s 2 Friction needed to give the 3 kg block this acceleration: f = 3 × 3 = 9 N Maximum available: f ma x ​ = 0.4 × 3 × 10 = 12 N . Since 9 < 12, the blocks do move together. Acceleration of the 3 kg block = 3 m/s². Answer: 3.00

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