Question

Two blocks of masses 1kg and 2kg are connected by a metal wire going
over a smooth pulley as shown in the figure. The breaking stress of the
metal is (40/3TI) x 106 N/m2. If g = 10 m/s2, then what should be the
minimum radius of the wire used if it is not break ?

Answer 1

Explanation:

Let tension in string is T and acceleration of system is a in left direction

Equation of motion of blocks

For 2kg block - 20−T=2a

For 1kg block - T−10=a

Solving both equations - T=

3

40

N

Stress in wire =

A

T

3π

40

×10

6

=

3

40

×

πr

2

1

⟹r

2

=10

−6

⟹r=1mm