# i couldn’t get the answer ?

Two blocks, A (weight wA) and B (weight wB), are connected by a lightweight cable. The table on which A rests is frictionless. The pulley is frictionless and does not rotate.

You give block A a push to the left and then release it. The cable remains taut as block A moves to the left, comes instantaneously to rest, then moves to the right. What can you say for certain about the tension T in the cable at the instant that block A has zero velocity?

Solution:

A. T = wA

B. T > wA

C. T = wB

E. More than one of these is true.

D. T < wB ✅

explain using equations plz 😅

### 2 Answers

- NCSLv 71 month ago
Hopefully you can tell that after you release block A, its acceleration is to the right. (Its velocity is INITIALLY to the left, but it reverses direction and speeds up, so it is accelerating to the right.)

By the same logic, B's acceleration is down. Taking "down" as positive, the net force on block B is

Fnet = mB * a = wB - T →where T is the tension.

T = wB - mB*a

and since mB*a is positive,

T < wB

(It is POSSIBLE that either A or B is also true, but we can't be certain given the data.)

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- Andrew SmithLv 71 month ago
The force available cannot be more than wB. But if that force is accelerating A it is also accelerating B and SOME of the force is used accelerating that. Therefore the force available via tension to accelerate A MUST be less than WB no matter what the situation.