Question

Two masses A and B are connected with two inextensible string to write constraint relation between v_A and v_B . 

Student A : v_A cos θ = v_B .

Student B : v_B cos θ = v_A .

(a) A is correct, B is wrong 

(b) B is correct, A is wrong 

(c) Both are correct 

(d) Both are wrong

Answer 1

Correct option: (a) A is correct, B is wrong

Explanation;

If student will use vector component (only mathe-matically) he/she may conclude both are correct. Hence the option (c).

Correct concept : Velocity of both ends of the string along the length of the string should be same.

v_B = v_A cosθ .