Particles of mass 3m and 5m hang one at each end of a light inextensible string which passes over a pulley. the system is released from rest with the hanging parts taut and vertical. during the subsequent motion the resultant force exerted by the string on the pulley is of magnitude

36.8 N

Explanation

tension in string when both bodies move vertically is given as

T = (m1 × m2 × g) / ( m1 +m2)

T = (5 × 3 × 9.81)/(5+3)

T = 147.15/8

T = 18.39375

SINCE TENSIONS ARE ON BOTH SIDES OF PULLEY AND ON PULLEY BOTH ARE DIRECTED DOWNWARD

HENCE FORCE ON PULLEY = 2 × T

                                               = 2×18.39375

                                               = 36.7875

                                                 = 36.8 N

when a device is used in a circuit in which the voltage is 81 v, the current flowing through the device is 3 a. what is the resistance of the device?

a. 27 ω

b. 40.5 a

c. 243 ω

d. 243 a

the correct answer is a. 27