Mechanics Question

2014-11-13 11:15 pm

Two blocks connected by a thread are being pulled horizontally by a force 40N as shown in. Assume no friction in between the floor and the blocks.

a)Find the tension T on the two blocks.
b)What is the acceleration of the 3 kg block?

Now we consider there are frictions between the floor and the blocks static friction coefficient u2 is 0.6 and kinetic friction coefficient 0.5
c)Draw the free diagram for 3kg and 5 kg block.

希望有數學高手解答,在此大大的感激不盡!請用英文作答!

回答 (1)

天同

2014-11-14 1:26 am

✔ 最佳答案

Since a diagram is missing, I assume that the 3 kg block is in front of the 5 kg block. The force of 40N applies onto the 3 kg block.

(a) Acceleration of the blocks = 40/(3+5) m/s^2 = 5 m/s^2
Hence, tension in the string connecting the blocks
= 5 x 5 N = 25 N

(b) 5 m/s^2 from (a)

(c) The block in front (3 kg block) is acted by three forces:
(i) 40N pulling force
(ii) tension in the string (in direction opposite to the 40N force)
(iii) frictional force (in direction opposite to the 40N force)

The 5 kg block is acted by two forces:
(i) string tension
(ii) frictional force (in direction opposite to string tension)

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